It's weird, it happens to me a lot for the last couple of weeks. It says oops rolled a 1 on our api check, come back after a short rest. The error code is: 

im having this same issue to, it was working then suddenly i cant load or edit my sheets

Same here.  at least two days it hasnt been working

Same, happened in the middle of a session as well. 12 hours straight now, can access on my phone no problem. Seems like someone dropped the ball somewhere.

ya same here, i got a session 0 tonight and havent been able to access sheets since yesterday.