Show/Hide Coherence Gmail app shortcut doesn't work

I have used Coherence to create a Gmail app (with Brave), and set up a simple shortcut to show/hide the app.

Showing works fine - although is a little slower in showing compared to real apps, however using the shortcut again does not hide the app.

I have plenty of these shortcuts set up that work fine for other apps.

Is there something I'm doing wrong, or some incompatibility with Coherence "apps"? I'd really like to make this work as it makes a difference with day to day use.