Not fully sure how I got this to happen, but I was jumping like the mad hatter would, and the bugged out to be stuck in mid air with my hands in the air.

This then allowed to me to navigate any terrain without any restrictions.

Will test for a few more moment, then report it then see if relogging fixes it.

Jumping over land will fix it, but if the player walked away from where it happened, the 'invisible wall' issue will stop the player continuing forward.