Yes, there is a db issue. I have (had) the same problem with POSTS. You need to access your db (mysql) with something like phpmyadmin (or the mysql command line).
Access the wp_users table and find your ID. Next, go to the wp_usermeta table and find the following fields for your ID in the umeta_id field. In your case, they might be the _page fields.
screen_layout_post
meta-box-order_post
metaboxhidden_post
closedpostboxes_post
I just deleted those for my ID (this is not tested in any way…always backup your data!). WP rebuilds them once you change the settings again.
If you want to figure out the bad bit, create a new user, make your changes (don’t change to one column), and compare the data. I just don’t have time to figure it out. Something in the json structure is not being updated correctly.
