Modpack version
1.80

Issue
EnderIO Soul Vial can be used on the Wither, even though this is blocked in the default config (then used in a powered spawner). Explicitly adding the wither line to config/enderio/recipes/user/spawner.xml fixes this, though that's probably not the fix you're looking for... This may extend to other default blacklisted bosses, but I did not check those.

Logs
N/A

Hmm, I haven't been able to reproduce this. Are you doing something special to capture it?

Nope. I downloaded 1.80 through Twitch launcher, and made a creative world. I set up the wither using JEI to make sure I wouldn't die, then changed to survival to finish the spawn.

I used JEI to get Soul Sand, Wither Skeleton Skulls, Creative Mill, Angel Ring, Soul Vial, and armor. I let it spawn, flew away to avoid the initial explosion, then flew back to capture it.

Hmm that's odd, I did the same :s

Also of note - all the supposedly banned soul vials show up in JEI, including bosses (Twilight Forest), Elder Guardian, etc., suggesting that something is wrong with how it's loading the config. Anything else I should check?

Nah, but thanks for asking :)

it has been this way for awhiiiiile... my server is on 1.74 and i have had a powered wither boss spawner for about a month now i think?

I actually like that it works in a Powered Spawner, what I don't like is being able to capture it easily :P

Correction - Twilight forest bosses, at the least, are not able to be captured in soul vials.

Ok, I can confirm, this still works. I made a creative world, took infinity armor, soul sand, wither skulls and soul vials out of the creative inventory, switched to survival mode, spawned the wither in survival and could capture it with a soul vial...

I managed to recreate it in a new world, still can't in my original test world for some reason. I'll try to disable it better :P

I have been unable to fix this issue I'm afraid.

@NillerMedDild Can you elaborate why you were unable to fix this issue?

I've overridden my spawner.xml file with the contents of the spawner.xml file on the develop branch (https://github.com/NillerMedDild/Enigmatica2Expert/blob/6da785fec132576f6ff37a6feb68334ae5d8c883/config/enderio/recipes/user/spawner.xml) in my (fairly new) Enigmatica2Expert 1.80 folder and after a restart of Minecraft it worked as intended for me:

Your fix works 😏

GitHub

NillerMedDild/Enigmatica2Expert

The official repository and issue-tracker for the modpack Enigmatica 2: Expert for Minecraft 1.12.2 - NillerMedDild/Enigmatica2Expert

Edit: Wow, sooo much context @unfurl 🤦 . What about the filename + Commit Hash + maybe a extendable file preview 🤔

Huh, that's... something. I was still able to capture it in my testing world. I'm glad it works :P

Just cloned the current develp branch (deca811), ran java -jar InstanceSync.jar (and manually downloaded Pams Harvestcraft). Then added the folder to MultiMC and added the recommended Forge version (14.23.5.2854). After starting Minecraft and setting up a world, the Soul vials were not able to capture the wither 😄 .