I am sorry to hear you're unable to edit the cells in the middle of your table. This sounds pretty campaign-specific, so I hopped into your account to take a peek. I found that I was able to type in the middle of your table. To test things further, I also added a new table and was able to type in all cells there too. But I'll admit that Emma was a little "sensitive" when I moved quickly between cells. Tables are pretty new, and as such, we are still fine tuning the functionality. Emma choked a time or two when I moved too fast, but as long as I worked slowly and methodically, I was able to type in any cell in both tables.
My recommendations are this:
1. type the text into each cell and avoid pasting text in a table
2. proceed slowly from cell to cell
3. review our table formatting tips here
I hope a little extra measure of caution will do the trick! If you need a hand with anything else, feel free to reply back and we'll take another look.