Customization Bar just Vanished - WordPress

[88TSi]

Describe the issue with as much details as you can.
If it's a bug, please give the exact steps how to reproduce the problem.

While doing edits in WordPress, the option to customize the content becomes no longer available. To be clear, the content literally vanishes and no one can explain it.

The problem is that several of my sites and customers are using Unyson and we all have experienced the same issue. When reaching out to the author fails, we're stuck reading responses from other that discuss this but fail to list the solution.

As detailed as we are, it seems that the author has all but abandoned us as the plugin appears to be no longer available and at this time, I don't see a patch available.

Any help with how to correct this would be great. So far, we have went back and restored previous versions, tried other plugins and etc. . . thus far, nothing.

Please advise.