Incompatible with my theme customizer plug in

I use ExtendThemes Mesmerize and Materialis themes. I love them and have used them for years. When I found your plug in to style WP Forms, I was thrilled. But, your plug in doesn’t work with my theme. I have to deactivate your plug in every time I do any other editing, and then reactivate it when I am done. Can you help by looking at what might be incompatible between the two? THANKS!