Appearance->Menus panel is broken with JS error
Greetings, I am having an issue with both Classipress 3.6.1 and 4.2.6. Our live site is here, running CP 3.6.1:
Our staging site is here, running CP 4.2.6:
In both sites the Appearance->Menus admin panel is broken - it won't show the column with the actual menu items - and does not allow for menus to be edited or created.
A screenshot of the panel with the error is attached. The system info report is also attached (for the staging site, version 4.2.6 of Classipress).
If I switch the theme to the Twenty Twenty-One theme, the problem with the menus goes away.
I can provide admin access to the staging site if you would like to look under the hood.
PHP 7.3.30, MySQL 10.3.27 MariaDB, Linux cPanel hosting