If you are using the default skin for your mount in an area or lots of players not fully loaded, you get stuck in the ground. If you move during this you can travel away from the camera and wait to load or travel far and then dismount to reset back to where the camera stuck.
This only happens with the default skins. There's some background loading involving skinned mounts that have you move around just fine.
I've been dealing with this for months thinking it would get fixed since the big bug everyone experienced at PoF launch got worked on.