Mobile Menu flashes open, then disappears

Hello,
I have been using this theme successfully for over a year, but a very strange change happened a few months ago seemingly out of nowhere…

The mobile menu is present, but when the menu is clicked, it opens for a quick second, then closes. It will not stay open.

I’ve tried deselecting & reselecting Mobile Navigation in the Menu Settings. I’ve even deleted the entire menu and re-created. I’ve tried switching themes, and it DOES stay open on a different theme. This seems to be only true to the Virtue theme. I don’t have any ideas left. Can you please help?

The website is https://sacredpathbirth.com/. Thank you so much.