Permanent Spectator mode glitch on login

Logged into my single player test world in gamemode 1. and upon login began sinking through the world. after a moment i can double tap to fly, but while i appear to be in creative, the game won't accept commands(can't even open chat or inventory) and thinks i'm in spectator
-thought this was odd, so i did some trouble shooting trying to replicate issue.

Can replicate on my end repeatedly, though seems random. thought it was a bug related to texture pack loading. but after several attempts it did it with defaults.

If it's related to the world somehow, it is attached. testing co-ords for this issue: -478.425 56 615.493 (where it occurred to me and repeated the issue.)

I can work around the issue by relogging into the world repeatedly until it 'sticks me in the right gamemode' properly.