In Ubuntu the window-frame R-click dropdown menu does not appear

Things I have tried

R-clicked all around the window frame. No joy.

What I’m trying to do

I’m trying to move my Obsidian window to my 2nd Desktop or All Desktops. The action appears on the window-frame dropdown menu.
Kubuntu 20.04 - Plasma display controller
Obsidian 0.13.31

This screenshot shows the window-frame R-click menu on a normal window.

Workaround: Close Obsidian, switch to the desired desktop, reopen Obsidian

Unfortunately, the frameless ui we us doesn’t support this.