I have a mod out now that can mark people to track them. It's at 10 now and I was looking to make it into 20.
Well, it seems that after the 16th. The quest markers in-world don't appear. THEY DO However show up on the
actual map screen. and the alias' do get added as they appear in the journal.
I split up the objective quest markers into two quests now, and after the first 10 are filled, the next 6 show, but the other 4 won't, until I start removing tracking markers.
If I untick the first quest that holds the 10 objective markers, the second set of objective markers on the 2nd quest, show up fine.
So my guess is, Skyrim is only able to visual show up to a certain amount of quest objectives at a time. I'd just like
some confirmation on that so I don't go crazy going over and over my mod as I have been doing for the last several days.

Thanks,
-Mush-
Edit: Testing wise, if you just tick on 17 or more quests or objectives and look at the map, that won't work because they do show up on the map. All 17+ makers would need to be in the viewing world at once to really check.