Dropdown menus disabled after 5.5.1 update

Hi, one of my clients contacted me to say that his dropdown menus were no longer working. I checked them and sure enough, only the top level menu items worked. I tried restoring to a 9/4 restore point and found it didn’t help, so I went for an 8/4 restore point and the menus functioned as expected. I went in, intending to update the core and plugins one=by one to see if and which one caused the menu to malfunction again but didn’t have to go that far. AS soon as I updated to 5.5.1 the dropdowns in the menu were again disabled. The site is using the Earth theme, and it has been kept updated. So I’m now restoring the site to its state on 9/17. Once that is complete I’ll downgrade the core to 5.5 so things are working for him and he doesn’t have to restore any content he would otherwise have lost. I’ll be happy to provide info from Site Health before downgrading the core in hopes this will help you figure out what’s gone wrong and how to fix it. Thank you very much for any help you can offer. I will also contact the theme dev and see what they have to say.

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