I have a paid account and am getting the exact same thing. I can't add any rows or columns to my bases. So frustrating. 

I believe we are on the free version as well and we have several bases going and are unable to add data to any of them. I emailed the help desk but haven't heard back. Frustrating as my tickets are piling up.

That's weird. So I guess the error is on Airtable's end?

I believe so.

Does Airtable have live support? This is stopping me dead in my tracks. 

It says it's live chat but the one I used was automated which was no help, so I emailed.

Same here. I thought they have live support but it will route you to send an email.