I have noticed that the Menu Manager extension is briefly displaying/flashing a vertical menu when refreshing or loading a new page. This behavior is observable here: https://www.loweprofile.com/gallery/ very obvious as it occurs at a slower rate. And here on a fresh install with zero code modifications: https://www.loweprofile.com/memorybook/

It seems to me that the 'vertical" menu used for mobile is briefly displaying. I am using the 'forked' iteration of zpBootstrap. This occurs on Chrome, Edge/PC or Safari/Mac OS.

Any help appreciated. Let me know if more info is neeeded.

This is a theme issue respectivly the bootstrap framework it uses as the menu manager plugin does not provide any styling at all.

The plugin is not actively supported by its developer. We do have a fork but we primarily fix actual ZP related incompatibilities.

I solved this issue. It is caused by the tidy-assets v1.1 plugin. I was trying it out to speed up the initial load time, but it caused display anomalies. Disabling fixed the issue.

Then this is not a menu_manager issue at all but of tidy-assets which is of course not officially supported.

Yep, just posting so the issue is documented.