I've been having this weird issue on a site for a few weeks now, tried everything I found by searching but still not being able to find a clue of the issue.
Whenever I add some items to the Menu (Appearance > Menus), a few items become empty. And then gets removed when I click the Save button again. Similarly, if I edit any posts, the same thing happens with the menu items.
Here's what I've tried so far,
- Increased max_execution_time, max_input_vars, max_input_time, memory_limit, post_max_size, upload_max_filesize, max_file_uploads in PHP.ini. I set those to very high numbers but still no luck
- Then I tried copying the site to another hosting and on my localhost, but no luck. Did #1 on all the environments.
- Changed the theme to default 2021 and deactivated all plugins, still no luck
- Checked the database, wp_posts table has 4.6k rows with size of total 10.8MB, with overheads of about 300KB. So, I tried changing the storage engine of that table to innoDB from MyISAM but the problem is still happening.
Is there anyone who faced similar condition? What could be the issue?