Workspaces: windows not presented/spread after certain sequences

[jacobgkau]

On both 5badae0 (master) and 6d111bd (gnome-40), after performing the following sequence:

1. Open several windows in a workspace.
2. Drag a window to a new in-between workspace.
3. Drag another window to a third (last) workspace.
4. Drag the window from the middle workspace to the last workspace, destroying the middle workspace.
5. Switch to the last workspace.

...the windows are overlapping (not presented in the spread they're supposed to have) and have no highlight on hover:

https://user-images.githubusercontent.com/7199422/128563715-5a1080d0-bf63-4c9f-9629-b719fc091f48.mp4