Glitch which effectively prevents you from keeping purchased skins

This bug relates to both community servers and skins. Mods are semi involved but i am not sure if they are actually the cause of this issue.
I am a member of the community server “Demons Domain (Friendly)” and i have been frequently logging on there to save up the necessary marks to unlock every single skin on all of my creatures, as i absolutely love collecting as many skins as possible and i enjoy switching through them a lot. Recently, i ran into a bug which now prevents me from properly unlocking skins, and from being able to utilise them normally after being purchased previously. The server uses mods and the bug impacts both official skins and modded skins, along with both modded creatures and official creatures. Every creature is affected, even if i make new ones. This is very upsetting as i had a lot of skins unlocked beforehand and i really wish to able to change skins at will. This bug only seems to affect me on this one single server, and i am unsure of how to completely replicate it.

The cause of the bug isn’t clear. It occurred after i had unlocked some skins on one of my herbis - all of my skins were suddenly just paywalled again and i couldn’t put them on again without marks.
Skins that were purchased before the bug began are now locked and cannot be equipped, unless you have a mark balance equal to the skin’s original price. When equipping the skin with the sufficient amount of marks in your balance, the game will take a fee of 150 marks (or differing amounts if it is a modded skin with different skin upgrade pricing) and you can then shed into that skin. But as soon as you click off it, it locks behind the same paywall again. All unlockable skins are stuck with this endless bug, which makes it difficult to switch skins on some creatures.

I am supposed to be able to freely look through and equip any of my many skins which i earned marks to pay for.