I'm playing on a modded server with a modpack I've created with friends.
in getting my first set of sturgeon eggs, and trying to spawn it, i found it vanished after roughly 4 seconds of being in the water.
They're also fine when on land, and will survive until they suffocate, but as soon as i push them into water, they will vanish after a few moments
aquatic dinosaurs are fine, but the fish seem effected by something. (i tested them all in creative, and only the fish +nautilus are broken)
I thought it could be Animania, and even after removing the mod, its still broken.
(can provide mod list +a recording)

so i am getting something "close" to this on 1.12 (if that really matters atm) and i noted its... only when IM in the water with them.... and its all strictly small aquatic creatures ... so all the fish, plus the nautilus... plus a good portion of the "small" aquatics from the "Prehistoric Nature" mod.... and can confirm this happens in survival.... i even went and found multiple live nautilus's that spawned and tried to "grab them" but... they flee and then just "vanish" .... but i noted that all the mobs iv "incubated/cultivated" would stay around... till i was "near them IN the water".... then they would ALSO flee and "vanish" aka despawn

sadly i cant find any clue on WHAT is causing this.... help would be appreciated ofc

HI @assasinwar9 - it's Rob the owner/dev for Prehistoric Nature (PN). I'm not able to help with Fossils and Archeology....... but, I noticed this over here on the Fossils and Archeology github and thought I'd ask if you would mind popping into our own Discord server for PN as well (at https://discord.gg/snzaYpu) for the PN component of this bug. The PN code is not the same as the FA code, even if you are seeing similar symptoms, though it is similar. It will take some back and forth with you and me to figure out what is happening if you are still seeing this bug in the latest version of PN. If you cant use Discord, happy to work this though on the main CurseForge page if you would like (https://www.curseforge.com/minecraft/mc-mods/prehistoric-flora). Thanks!

I'm sure the FA people will be in touch about this, and if we solve anything in PN that seems like FA need to know, I'll of course pass it on.