Steps to try and resolve the current issue
1.	The best solution is to send the mounts up with the drop pod they came with and then try to bring them down again. (Rinse and repeat the process until the mounts move.)
2.	Restart your session or server
3.	Place the mount on follow and move 400-500m away you until it teleports to your location (4-5 grid squares). If you already have a mount on world sometimes getting on and off the mount while riding away will speed this teleport mechanic up


True resolution I would like to see 
1.	Either fix the problem in general which I feel is unlikely since its been around so long
2.	A simple solution is treat the mounts / animals you bring down just like the workshop animals and have them placed in Cryo pods that are deployable assets. Meaning you can carry and deploy when ready and would fully resolve this insufferable problem while keeping the game mechanic consistent.