If you have an object with a ScreenGui child on the server, and you clone said object to any Players Gui, they will be able to see the Gui but all the interactables will fail to function.
Simple Repro:
Result: (no input detected)
Same thing but done on the client side: (it works)
Addendum: if the server reparents it to the playergui afterwards, it will resume working like normal.
HOWEVER!
if the client reparents it to the playergui from its side, it will still not work.
Addendum 2: Thanks to hello42, It seems if the server waits an arbitrary amount of seconds before parenting to the playergui, it will work.