Having a solid fuel jump jet break while riding a hoverboard can get you stuck mid air.

[AaronJFluffyBuns 0]

I was riding a hoverboard and using one of the solid fuel jump jets. The fuel was low and it ended up breaking while i was mid air. After it broke, it got me stuck mid air.

If you want to reproduce this, use a low-fuel solid fuel jump jet while riding a hoverboard. Im not sure if you have to be mid air to get stuck but using the jump jet forces you up anyways.

[AaronJFluffyBuns 0]

RE:
If you exit the save and reload it, you should be un-stuck