For redundancy I IWT with all characters and have quest sharing on.
Before now, either system would accept the quest for me.
With the last beta, if I did the same, I would see my master sharing and getting the

"Sharing questnumber3 with characterb"
"characterB is busy"

CharacterB get stuck with no quest, the quest window open and no buttons working on that said quest.
Have to close the window and start again.

I can retest again share only works and if noshare/IWT works.