Occasionally the camera position does not match the player's model's head when seated, causing you to view your body from a very high position when you have the First-person Model mod installed.

I did some testing on a completely blank instance save for personality and blueprint and it worked, what other mods are you running? Because its doing this on my main modpack too.

I don't think its an issue on First-person model's end, nor personality's for that matter. there must be some other mod screwing things up.