Chaos guardians either spawn in pairs and work fine otherwise, or spawn singular and will permanently despawn (conditions not certain, haven't gotten one to stay long enough to break all the iron+slab cages)

Additionally guardians despawned in previous versions don't respawn, despite the chaos crystal still existing (and being shielded)

DE Version: 2.0.9.192
Pack: Direwofl20 1.10 pack with certain mods manually updated (including DE)
This is on a server.

Addendum: Singular Guardian seem to despawn after a some amount of time.

I just fought one, and it straight up disappeared while I was looking at it.

Ok.. .What? I though i fixed this... This must be some kind of interaction with another mod. Does anything get printed to the console when it vanishes?

05.04 23:55:52 [Server] Server thread/WARN Tried to add entity draconicevolution.ChaosGuardian but it was marked as removed already
05.04 23:55:52 [Server] Server thread/WARN Wrong location! (622, -4377) should be (625, -4375), EntityChaosGuardian['Chaos Guardian'/143991, l='world', x=9964.41, y=138.37, z=-70022.57]
05.04 23:55:39 [Server] Server thread/WARN Keeping entity Enderman that already exists with UUID 0440b781-4ffe-4b2c-bddb-920f577376ac

Can confirm both of the same problems still happening. ATM:Expert 1.033B multiplayer. DE version 193 latest

Can confirm, I'm having the dragon despawn on me. We had it happen twice in a row. I'm running a FTB Beyond server.

21:27:55  [Warn] Wrong location! (-2, -627) should be (0, -625), EntityChaosGuardian['Chaos Guardian'/980337, l='world', x=-30.87, y=154.95, z=-10017.42]
21:27:55  [Warn] Tried to add entity draconicevolution.ChaosGuardian but it was marked as removed already

22:08:12  [Warn] Wrong location! (-4, 626) should be (0, 625), EntityChaosGuardian['Chaos Guardian'/1453447, l='world', x=-54.12, y=133.53, z=10021.99]
22:08:12  [Warn] Tried to add entity draconicevolution.ChaosGuardian but it was marked as removed already

Specs:
Minecraft: 1.10.2
Forge: 12.18.3.2254
FTB Beyond 1.5.3.
DE 1.10.2-2.0.10.193-universal

Managed to fight a singular one to its death in 193. Confirms that it's not guaranteed/reliable for it to despawn.

I am getting the same error on FTB Beyond 1.5.3. DE verson: 1.10.2-2.0.10.193 (2.0.10)
[01:02:51] [Server thread/WARN]: Wrong location! (625, -622) should be (625, -625), EntityChaosGuardian['Chaos Guardian'/11315552, l='world', x=10011.50, y=183.20, z=-9948.29]
[01:02:51] [Server thread/WARN]: Tried to add entity draconicevolution.ChaosGuardian but it was marked as removed already

When a duplicate appears, I also get this in the log:

[07:39:13] [Server thread/WARN]: Keeping entity draconicevolution.ChaosGuardian that already exists with UUID ab38d482-ac4d-4934-8be7-44816378d009

When killing one of the two Chaos Guardians that appeared at the same time, one of them created one of those "Whoever is screwing with the dragon you need to fix your shit!!" exceptions, and I'm 90% sure it was actually the one I was fighting from the start, which I guess is likely to be the duplicate since it usually takes a few seconds before I can actually see the Chaos Guardian.

edit: Also running on FTB Beyond 1.5.3 btw

edit2: I also feel like this usually happens when they suddenly decide to move quite fast (instead of circling/chasing you). Then again, I've also had it happen before I actually saw it (which was when I thought it might be due to ungenned chunks, so I circled the island before actually going there).

Playing on a server running Direwolf20 1.10 pack and this happened to me three times. Two times it was the dragon vanishing, and one time it was doubling. Just had the third occurrence happen where it vanished mid-fight. I did get this from my server's log if it helps:

[20:43:58] [Server thread/WARN]: Wrong location! (-626, -9) should be (-625, 0), EntityChaosGuardian['Chaos Guardian'/4313001, l='world', x=-10004.95, y=265.91, z=-134.23]
[20:43:58] [Server thread/WARN]: Tried to add entity draconicevolution.ChaosGuardian but it was marked as removed already

The pack is only on DE version 2.0.10.199 for the latest non-beta release (maybe should be 2.0.10.194?) so not the latest I see here.

I also have this happening, but I have not been watching the log files. I am using the FTB launcher to launch FTB Beyond 1.5.3 (not which specific version of Draconic Evolution). The only thing I have changed is I added DynMap to the server for mapping purposes, and made a few config changes in other mods (elevator distances, number of chunks I can load, stuff like that), but nothing to Draconic Evolution.

The first island I went to, I didn't know what I was doing (first time killing a chaos dragon), so I ended up teleporting home using an Advanced Dislocater. Once I got my bearings and figured out what I was doing wrong, I flew back to the island, but there was no dragon any more. Flew around the island to see if he happened to just leave the area, no luck. When I came back to the center of the island, the animation of lightning hitting the spires and blowing them up was happening, to all but 3 of the spires. The crystal was still shielded.

I decided to immediately fly to a second island, and thinking the TP is what made it break, I stayed this time. Was flying around, breaking the spires, then suddenly noticed the healthbar disappear, and the "fog" that appears with the dragon vanished. I didn't stop moving, but I started looking around, and sure enough I couldn't find the dragon. This time the spires did not blow up, and there were even some spires that I had not made it to yet to break. I flew around, broke them, nothing changed. I TP'd away, then back, no difference.

I am going to start recording my Minecraft gameplay, so when it happens next I can either post the video, or at least review it to get some decent screenshots. I might even try to have the server console in the video feed also, just so they are in sync. Gotta love NVidia's built in recording feature in the newer gen GPUs.

I'm pretty sure this has been fixed in a recent version of DE, try manually updating it and see if it continues.

I am currently playing on a server version of Infinity Lite 1.10, We are currently updated to version 1.8. I have now consecutively gone and fought 2 separate chaos guardians both of which double spawned. This time I actually died cause of lag lol. But, with all this being said, I managed to pull the Console log from immediately after the fight. Here it is.
Chaos Error log.txt
Hope this is Helpful Brandon, as I love this mod.

Just downloaded the new version along with the latest version of brandon and chickenlib for 1.10 .... still have two chaos guardians chasing me around at all times.... very..... very.... frustrating

I just looked in my mods folder which is the same as the one on the server and this is the name of the .jar file Draconic-Evolution-1.10.2-2.0.9.192-universal.

@sloppysailor Is that a new island? because the update wont remove duplicate guardians that already exist.
@FluxAdept Its not fixed in that version, Its fixed in 2.0.12.222

so because the server I run is up to date on the modpack version, how do I go about fixing this? can I update the .jar on the server and itll be okay? or will that bring back mod rejections for clients due to them not having the updated version of DE on clientside?

What DE version is the pack running? To find out go to Mod Options (Next to the regular options button) and get the version. Or just open the mods folder and check the jar version.

This IS Fixed in the latest version.... Unless this is a new issue... I hope not...

You will need to update mod server-sided and anyone that will need to connect will get notification that they need to update their DE. So to answer your question: Yes I believe that client update will be needed, but if you are running using Twitch Client it is basically matter of few clicks :)