When i mouse over any of these quests i don't get a tooltip

If i do this on the liverealm, i can see tooltips.
There is no obvious lua error being logged.

Which game are you using?

Sorry. I should be more clear. I have assumed it is 11.0.5 PTR because of the title, but when I login I can see tooltips on all three places: (1) the Wholly Quest Log entries, (2) the QuestPanel an NPC presents (using the quest number Wholly puts in the top right), and (3) the entries in the Blizzard quest log.

This doesn't affect all quests, it is just by chance that all of the ones in the zone don't have data displayed, in a larger zone like Suramar i get it every other quest but it seems random.

I see what you mean.

Wholly is basically doing the following:

GameTooltip:SetHyperlink(format("quest:%d", questId))

However, there are times when that fails with specific quests. And what is interesting is sometimes when you come back to a quest it will start working again. However, this does not happen at all with quest 41167 in my experiments.

When i try the same zone on the 11.0.2 live realm, no problemo. So this is so inconsistent that it is hard to get to the bottom of it.

When I try 11.0.2 live from Hallowfall explicitly using Wholly to search for quests 41166 or 41167, for example, both do not show me tooltips. When I run my test code to show the hyperlink for those quests neither shows anything. So there seem to be some quests for which the SetHyperlink does not work.

That does not have anything to do with missing quest data in the local cache, does it?