My ID is grimeden.
I just had this happen to me with square J11. It was the last expansion plot I had available, and now it is not open and I do not have the expansion icon anymore. When I click on my Royal Points info and select Expand Your Kingdom, I get the popup that I have no plots left. I tried force closing, turning off the iPad, and reinstalling. None of those steps resolved the problem.
What happened was: I gave the final items on the check list: 3 expansion permits. I then saw the green checkmark to open the plot. I pressed it and the plot opened: I could see rocks and trees. Then the game auto-synced, and the plot disappeared. I looked in my inventory and noticed my 3 permits were used, but I could not expand to that space anymore and it was not open to me to use.