At least these two quests are broken by PfP (still need to test on vanilla):
Blood Ties - when you give the potion to Sinyaramen, nothing happens and there’s no console output. He doesn’t take the potion and the quest does not advance. (Need to confirm this is PfP). This is not PfP, it’s something else... A grep through my mod dir shows thatThis is caused by “Wait and Sleep for OpenMW”, though I’m not sure why.
Tamriel_Data.esmalso has a reference to “Sinyaramen”.
Not a quest but you can’t get Eltonbrand due to the changes PfP makes to this (confirmed PfP bug, though I need to make sure it is specific to PfP+OpenMW).This isn’t broken either; it just takes a moment to process.