I have had the same thing happen but to all tamed / Bred dinos.

Cure on my server is to not lvl them up until after a server restart.
I restart my server 2 times a week unless Game/mods update or by request.
This Locks the dinos stats.

its called stat overflow on dinos too high in stats, they reset. u can see it happening on all ark dinos not this mod

I am now crying i dont wanna loose my bred dinos stats i worked so hard for them to be op. So as long as i wait to level them up untill after a reset ill be fine or im screwed either way

this was happening to my players (well still is) on Annunaki. Even just running Annunaki we have the same issues. Pegi is correct. I stated the issue on Annunaki as well and they blamed me and my config, even tho, its default. Anything over ganing 255 levels / stats it will bug out and cause this. I do not have a solution for it. I can only state, its not the mod, is the core files that are causing this.

oh and that server restart thing wont help you.