If you use Autoptimize plugin and notice any issue with the WP Mobile Menu try to exclude the WP Mobile Menu scripts from the Autoptimize process.
Copy the code below
/wp-content/plugins/mobile-menu/
If you want to be sure that is something in the Autoptimize settings add the following string to the site URL. It will deactivate the Autoptimize in that request.
?ao_noptimize=1
It will look like this
https://www.wpmobilemenu.com/?ao_noptimize=1