There are actually tons of quest related bugs.
Get Junior - Cannot talk to Roche
Skellige's most wanted - The Werewolf won't die so the quest never finishes.
Novigrad Closed City - Quest Failed
Reason of State - Quest turns failed when starting "On Thin Ice"
Hey, you wanna look at my stuff? - Cannot interact with the merchant
Black Pearl - Nidas dies before you can reach him so the quest cannot be completed.
There are so many and in various severity, that it's not even funny. A had completed quests in 1.06, that now in 1.07 are impossible to complete.
BTW have you finished "Find them all" ? Because I cannot.
Then the Killer Whale potion should help .I noticed (quite by accident) that in the Black Pearl Quest that the Drowners did not innate their attack until you surfaced. If you plan your final dive IE: id the location of the black pearl without taking it ,then dive with best breath potion in stock... it's possible to get the pearl and head towards the shore UNDERWATER ...once you surface the clock starts ticking.