PS4 500gb (312gb free space). Connected to internet. Signed out of PSN. Career mode easy. About 2 hours into the game session. No quicksaves only persistent saves.
Landed on Mun in the Midlands with Jeb. Collected 14 experiments, mostly from my voyage to mun, to put in my command pod. After that I went to the surface about 2k away from my craft to plant my flag.
Once I planted it I was not prompted to name the flag I could only read the empty flag. "Autosave" appeared. My resources tab went blank. I couldn't move Jeb. I couldn't access any menus after pressing options. I could take down the flag.
I forced closed the game and restarted. It rolled me back to my escape trajectory out of Kerban to the Mun. There was an autosave when I was in Muns SOI that did not load. So I was rolled back 3 autosaves.
PS loving the game anyway. With a few tweaks it will be a game I'll be playing for a long time.
Possible fix: Tested and it happened again. When this happens accelerate time to max. I waited one mun day. After that I still unable to move, however I was able to "quicksave". Close the game. Restart the game. Load quicksave. I regained all movement, UI, and menus.