So a bit of a weird problem. I was getting super blurry ground textures, so I thought i'd turn bing data off then on again. Problem is, as soon as I turned it off, I lost all ground textures. It's as if i'm in the middle of the ocean - it's all blue. Nothing seems to change it now.

 

Has anyone seen this happen before?

Yep, I have seen that perhaps twice. Been a while but it is as a result of losing your connection with the servers. Probably nothing wrong your side so don’t make changes. Servers are a little insufficient to deal with demand. You can try re-enabling all online services in the menu to get everything back to normal. Might work, might not. You will be unable to land with it like that.