Constant Basic Authentication Popups

Thanks for such a useful plugin.

I’ve recently installed it on a new development website where WordPress is installed in a subdirectory, using method 1 detailed here:

Giving WordPress Its Own Directory

The website root is password protected with basic authentication.

All was working as expected until I installed the Custom Permalinks plugin. Since then, when editing a post, the basic authentication username/password request constantly pops up when trying to save a post.

Any idea why this might be happening?

I’ve tried disabling other plugins and changing to the TwentyTwentyOne theme, checking the .htaccess files etc, but the only thing that fixes it is disabling the CP plugin.

Thanks