Oops… it should not say permalink, but slugs.
That popup is definitely not from WordPress.
Please attempt to deactivate all plugins and switch to the default Twenty Twenty-Three theme. If the problem goes away, re-activate them one by one to identify the source of the problem.
If you can install plugins, install Health Check. On the troubleshooting tab, you can click the button to deactivate all plugins and change the theme for you while you’re still logged in without affecting normal visitors to your site.
James Huff – thanks for replying.
Done all that in the first round with Toolset.
Even began over with a clean WP.
Even with all (but standard security plugins) deactivated, on a clean installation, this happens. No other development yet.
If the same thing happens with a different plugin on the same functionality, either both plugins have independently the same code problem, or there must be something in WP that cause both to do the same thing. Really strange that both give exactly the same problem, more or less at the same added data amount.
Could there be a default memory limit on taxonomy that needs to be increased?
Ok, so it sounds like you’ve narrowed it down to these specific plugins.
I recommend reaching out to support for the plugin you want to use, they’ll be more equipped to narrow down the cause.
The problem is the drop-down interface showing the list of taxonomy items. The drop down does not have the capacity for large numbers. A different type of interface is required. Instead of a drop-down a list such as on Page/Post pages would solve this problem.
Been in contact with plugin guys. They say they use WP UI, so it is not their problem.
BTW, other plugins we tested that use a different UI can handle 800 items without problem.