Quests 1641 and 1645 are repeatable quests to read/replace the Tome of Divinity.

They are never recorded by the server as complete.
If they are left with no further action, the blue ? Shows for paladins of the appropriate race, and the Wholly Log shows them as incomplete.
If they are invalidated, the downstream chain shows invalid.
Ideally, when the quest list is reloaded or the "downstream" quest is turned-in, they should be somehow forced to display as turned-in if the appropriate quest is returned as turned in.
The pairs are 1641 with 1642, and 1645 with 1646.
I have not got my paladins to 20 yet, but it looks like a similar circumstance may occur then.

Did you take care of making the downstream quests when completed mark the upstream ones completed in your last pull request?

My pull request was purely data, no programming.
So, no, it's a programming task,
Suggestion is to have a small table with a definitive quest and the awkward one, if xyz is complete, then abc should be marked complete.
But I really don't know Lua to any degree, so there may be a better way.
Right now, using my data file, there's a blue ? that persists.