Been looking at this for a bit this morning... I'm catching this exception in my BugBag:

2x PersonalBlacklist/Core.lua:397: hooksecurefunc(): UnitPopup_ShowMenu is not a function
[string "=[C]"]: in function `hooksecurefunc'
[string "@PersonalBlacklist/Core.lua"]:397: in main chunk

Locals:

Looking it up, it seems that the hooksecurefunc() had an API change that locked us from hooking into a few things, but I think thats a red herring and really the UnitMenu_ShowPopup was a function and its been removed or hidden.

Pumping this because the addon is still broken, would be incredible if someone could help fix it.

Edit: In the meantime, found a fork updated a couple of days ago by someone (huge ups to them), if anyone else comes by this.
https://github.com/Marechoux/Personal-Black-List-PBL/releases/tag/3.7.8