I've been having an issue with AMM and SP PageBuilder modules. It's a little inconsistent but often when I edit the PB module and save it, AMM stops loading.
The only way I'm able to get it to load again is if I re-install AMM.
Sometimes it also throws a "Your are not permitted to use that link directly to access that page (#450)." error, kicks me back to the module list view and the item remains checked out.
If I disable the AMM plugin, the the error no longer triggers when editing and saving PB modules.
Advanced Module Manager will change the urls in the admin from using option=com_modules to option=com_advancedmodules.
SP PageBuilder modules probably force the url to option=com_modules after saving.
Then the core module manager wil show.
To get back to the Advanced Module Manager, simply navigate away from the core module manager (so go to the dashboard or some other admin page), and then go to the module manager again.
Or just change the url from option=com_modules to option=com_advancedmodules.
So you do NOT have to reinstall Advanced Module Manager.