Twenty Seventeen v3.4 problem with mobile menu

Hey @bmpashley! Do you have any plugins that might be conflicting here. I have not been able to reproduce this on a fresh site with this theme. The best way to find out would be to deactivate all plugins, or to use a plugin like Health check.

If you can install plugins, install and activate Health Check. It will add some additional features under the menu item under Tools > Site Health.

On its troubleshooting tab, you can Enable Troubleshooting Mode. This will disable all plugins, switch to a standard WordPress theme (if available), allow you to turn your plugins on and off and switch between themes, without affecting normal visitors to your site. This allows you to test for various compatibility issues.

There’s a more detailed description about how to use the Health Check plugin and its Troubleshooting Mode at https://make.www.ads-software.com/support/handbook/appendix/troubleshooting-using-the-health-check/

Thanks for your help @properlypurple

Following your instructions with the Health Check plugin, I isolated the problem down to incompatibility with a particular plugin (WP-Optimize). I tried refreshing the WP Optimize caches and the browser cache but the problem continued, so I have disabled that plugin and posted the issue on the WP-Optimize forum for assistance. The theme is now working for me without that plugin enabled.

you can solve the problem by deactivating minimization of css styles in WP-Optimize