This past weeks I adapted my home made theme using several global areas in each page type. I uploaded the theme and it installed just as expected. I added content to global areas on one homepage. I encounted a an unexpected error 'unable to get permission key for view_edit interface'. When this happened, the content was added to the global area correctly. I clicked edit again and could save without problem.

All content is displayed on all pages using these global areas and global stacks are visible on the dashboard.
But on my homepage there is one occasion where a block (the AddThis block) in a global area is not displayed correctly (i.e. aligned left where it should be aligned right as it is on the other pages).

I removed the block and tried adding it again several times from different pages but this didn't solve the problem. On the homepage it's still aligned left instead of right.
I've tried to add a small image instead and this too would be on the left on the homepage and on the right on the other pages. When I try to edit design on the homepage it displays that it is aligned right while the image shows up on the left.

Can anyone give me a clue on how to correct this? I attached some screenshots including one from logs. There are two identical entries on the same day. Only one of them is in the screenshot.