I believe I have the necessary achievements, but the Luminous Pearl item to start the quest does not drop.
The only requirement I am unsure about is “must be level 110” since the pre-patch squish not sure if thats the problem.
Guide I’ve been using:
https://www.wowhead.com/the-underlight-angler-a-step-by-step-guide-to-obtaining-legions-fishing-artifact
110 is now 45. What level is your fishing skill at for Legion?
From what I can see on Wowhead, you need a Legion skill of 100, and to be character level 45 for the Pearl to be “caught”.
Side note: When looking at the wowhead comments, sort by newest first.
Your alt must be 45 minimum with maxed Legion fishing as well as having fished up all the Legion rare fish.
Sometimes, logging out and logging back in will prompt the pearl to drop. Even so, it can take quite a few casts into pools before you do get it since random is random. I’ve gotten several alts the Angler since the pre-patch dropped and can confirm the pearl does indeed drop.