A few things you can try:
- Network disable all plugins other than Pressbooks to see if the problem persists.
- Switch your book to the “McLuhan” book theme (the Pressbooks default) to see if the problem persists.
- Add this line to
define( 'WP_ENV', 'development' );to enable some extra debugging features.
Other helpful tools:
- Xdebug is an excellent tool to help with debugging PHP issues in your IDE.
- BrowserStack can help you test the appearance of various changes you've made across multiple devices, operating systems, and browsers. We especially appreciate its ability to set up an 'OS + Browser' combination and quickly test changes on local or test environments without having to set up and run a virtual machine.