Can't get Geckolib to work with Minehut server

[fuzzydreamin]

Exactly as the title says.

I play on a minorly modded server with some friends (hosted by Minehut, ofc) and we wanted to add a mod that required Geckolib, but experienced issues upon doing so. Specifically we kept getting a "no captcha rooms available" message when trying to enter the server with the new mods active. 

Did some troubleshooting and figured out it was Geckolib causing this issue. The modpack runs just fine on a fresh singleplayer server, so it doesn't seem to be an issue with the mods themselves. Some googling led to this issue apparently having come up in Minehut before, with the forums here being the only place I've seen this specific issue. So, my thinking is that it must be some incompatability between Geckolib and Minehut itself? 

Can anyone confirm or deny this theory, with an explanation for why it is happening, and maybe how to fix it?

(Specifically, the mod we needed Geckolib for is Mythic Mounts, if that information helps at all. We have also been able to add a mod that didn't require Geckolib, so adding mods in general isn't an issue.)

Edited November 28 by fuzzydreamin