If a cell is moved away in screen configuration, and then on the empty space new cell content is created, then the new cell will not be saved.
See screenshots:
1 - Right after opening screen configuration
2 - The upper right diagram is moved to the cell below
3 - "Change"-Button is clicked on the UPPER right cell (but dialog appears on bottom right)
4 - After hitting "Save" button, the newly configured cell content disappears and the content that was moved is there again.

Workaround:
Move content, leave configuration page, enter page again, add content.