I believe some of the landmarks don't unlock on the map until you kill a certain bounty hunter

[catloverplayer]

For the longest I only liked one landmark in Calvary Key to unlock the shadow head. The question mark didn't appear on the map till I beat Percy Medcalf the bounty hunter. Now I only like one landmark in The Gulf and no question marks are showing up. I'm assuming I have to beat the last bounty hunter. Once I find this landmark which gives the cartlege evolution I'll have all landmarks in all of the locations found.

 

[Rick9038]

For the longest I only liked one landmark in Calvary Key to unlock the shadow head. The question mark didn't appear on the map till I beat Percy Medcalf the bounty hunter. Now I only like one landmark in The Gulf and no question marks are showing up. I'm assuming I have to beat the last bounty hunter. Once I find this landmark which gives the cartlege evolution I'll have all landmarks in all of the locations found.

Well, I found that the question marks show up when you use the sonar perk and are close enough to the land mark. If you are close enough and depending on how upgraded your sonar ability is, it will then pop up point of interests on your map. That's, at least, what I seen. I hope that this helps..... P.S. I also think that if you beat all the objectives in the area, it may show all of the question marks of the point of interests but don't quote me on that. Lol

 

[catloverplayer]

I'm using max sonar which is topped at level 5 at the highest upgrade. It may be caused by a bug as well.

 

[Rick9038]

Could be.... seems to me that more people are starting to experience bugs.