When using either the UGX Modtools perk prefabs or the Zombiemode perk prefabs, the perks appear normally with the "The power needs to be activated" text on it. However, when the power is turned on all the models are invisible, and buying them is very weird. When you do buy them, the points are removed but there is no bottle animation and no perk is given UNLESS you receive a weapon from the mystery box. MakeCents in this post: https://zombiemodding.com/index.php?topic=20097.0 seems to be describing the issue but doesn't provide any information about the exact models/animations to add to the mod.csv file.

Nigge, i haven't had this problem before, but what i would suggest you to try is to:
1. Uninstall the mod tools
2 reinstall them, from UGX-MODS Confluence - ALL IN ONE link
3. Click the converter button in radiant before you do anything and leave it to finish
4. Use a script placer
That's it, i have never got that error before, so i am assuming you have downloaded the mod tools 1 by 1 by their versions, etc. Just try doing these what i said, and make sure to also save your map and all files that you need before uninstalling the mod tools. Except these, i don't know what else to say, have a nice day/night/evening etc whatever you want.

I reinstalled them and that seemed to work. Maybe the model got corrupted or overwritten