Using the WP mobile app with PressBooks

After a good bit of trial and error, I discovered that PressBooks is preventing me from being able to use the WP mobile app (Android) with my site. Is anything known about why this is the case, and more importantly, is there a way to fix it?

The error I get occurs upon any attempt to log into the site with the mobile app. I put in the URL of my site, then it asks for my username and password. When I enter it, I get an error that says “Error while adding site: GENERIC_ERROR”.

WP says this is most often caused by XML_RPC being disabled by the host, but that is not the case with my host. Next most common is a plugin or theme. Well, I ran the usual plugin test, disabled everything, and the only one that causes the problem is PressBooks.

Any help or suggestions would be appreciated!