So, for about 2 days now whenever I try to open the quest tab the game freezes and I'm thrown out of the game. If I open the game again it's as if I closed it myself, getting back into the game like it didn't run before.

I can only assume that there is an issue with a certain quest or some quest combinations. It can't be just one quest combination as I have been able to complete one quest (sell 13 weapons/outfits) and the issue is still there. Maybe it's having two bald dwellers, the quest counter has been reset in the meantime. No idea what the third available quest is.