Player mini not saving when set by GM

The GM is able to set the mini for their players, and when doing so can set it to any mini, including ones the players don't normally have access to, like the dragon. The bug is that upon leaving the table, the mini will be reset to whatever it was before the gm edited it.
Should be easy to replicate, however you do need two seperate people, as the GMPCs are unaffected. Steps to replicate:
1 - Add a character to a table.
2 - Have the GM change the mini.
3 - Remove the character from the table in some way. (Exit table button, close tab for a while, party kick.)
4 - Put the character back in the table. It should now have the mini reset to whatever it was before the gm edited it.
My browser version is: (do not change)
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.1.1 Safari/605.1.15

I believe the mini the GM changes it to only saved when xp is given to the character.