Having trouble with the Throwing SI:7 Off The Trail quest. I've completed all but the Suramar objectives and after several weeks of checking in, it's not loading to the Quest Board. Is there a prerequisite I'm not thinking of?
No, there is no further prerequisite if you're already on that quest. If there would be one you wouldn't have been able to pick it up in the first place.
There are two things that I can think of.
If you're in the middle of an artifact quest for any weapon (current or off-spec) complete it first. I've seen the quest missions not showing up for some reason while working on an artifact quest. This happened on my rogue as well as on two of my shamans.
Another thing is to send your followers on other missions. It has been reported on the official forums and on WoWHead that those missions tend to pop up after sending your followers away to do another mission. Just pick missions with a short duration so you don't lose much time.
If both solutions don't help open a GM ticket to request help. This would at least save the time to abort the quest and start over.
Or if you just can't wait any longer...
Abandon the quest and pick it up again. Start over and try again.