Observed Behaviour
When checking my currently generated world I found area that "soft kills" MC. I can still move around, but I can't attack any mob, can't receive any damage, no chunks will be generated or loaded. When I try to break block nothing is dropped, and snow as well as grass are just "floating". Similar with gravel and TNT. See attached pictures.
If I try to save and quit game is stuck in never ending "Saving world".
If I remove any of the mods mentioned below area that cause this issue works normally, but its impossible to confirm that it is fixed, as I suspect that generation slightly changes and problematic "something" is moved to different location.

Crash log:
https://pastebin.com/Fdca0kZ4
https://pastebin.com/HUCYnFnK
One of the mods mentions minecraft:bigdungeon, but i couldn't find it in sources of mentioned mods.
I know that there is no clear "error". Nothing else is generated in log.

Expected Behaviour
Problematic area works normally. I expect its issue with some dungeon generated by this mod/this combination of mods.

Minimal setup needed to reproduce

• Forge version: 1.15.2 - 31.2.46
• Mod configuration: default, I didn't change anything.
• Mods required to reproduce:
  astralsorcery-1.15.2-1.12.11
  BiomesOPlenty-1.15.2-10.0.0.366-universal
  curios-FORGE-1.15.2-2.0.2.6
  DungeonCrawl-1.15.2-2.2.1
  mgui-1.15.2-2.1.1
  observerlib-1.15.2-1.3.1
  tetra-1.15.2-2.18.1

Steps to reproduce
seed: 157733132531422357
X: 400
Y: 120
Z: 800

Create world with those mods, seed and travel to specified coordinates. I just do /tp 200 120 600 and fly there.

Since noone else has added onto this or idk what to do about this, i'll close this for now.

I couldn't reproduce it without DungeonCrawl and Tetra so I created bug reports there too.
mickelus/tetra#239
xyroc/DungeonCrawl#51

Uncertain what exactly this is..
The behavior you described would suggest a heavy lag or probably a infinite loop on the server thread. Thus the client still runs fine while the server is endlessly busy.

@HellFirePvP Yeah. It also seems to happen when new chunks are generated. I managed to get it with way more mods in different location when I explored. If you want me to check something, see it for yourself etc I can easily reproduce it.

I'm not sure i can do a whole lot about it? i'll take a peek when i get the time.

Can you pastebin the serverlog from this occurring?

@Doomgull Everything I provided till now was in singleplayer. I'm just preparing to put stuff on the server.

I did not have great success trying to reproduce this..
Same mod set and as you can see, same hillside.

I dont even know what to say. I will switch Tetra to Silent Gear, start my server and hope that me and my friends wont ever find this bug again. I think you can close this.