If I double-click on a module to full-screen it, the Audio Montage controls (view, edit, insert, process etc.) toolbar goes missing, and I don’t know how to get it back other than by closing WaveLab and re-opening. If this is a feature, where can it be turned off? If this is a bug, can it be fixed? 
I am not sure what you mean. On your video, from the start, there is no menu bar. Is it because you lost it, or is it because it is not included in your video?
If this is not the problem, on your video, you go full screen on a tool window and then back to normal. So apparently you know how to do it. So where is the problem?
Can you not see in the video that the section with all of the montage controls (whatever that section is officially called, I don’t know) is first there, but when I then double-click on “tasks” (just picked that one at random) to full-screen it and then double-click again to go out of full-screen, the montage controls are not there any more? I’m circling around the area with my mouse if it’s not apparent enough what has changed.
How can I get the control strip (is that what it’s called??) back when it vanishes, as it does in the video?
@PG1 the whole Tabs section above the main Audio Montage window is missing, as well as the Command Bar and the buttons for Maximize Window and Layout Options.
I can also reproduce this issue on my Windows 11 Pro PC, WaveLab Pro 13.0.20. This affects the Audio Editor window, too.
The Command Bar seems only to disappear, when its position is either set to Top Right or Bottom Left.
I’m not sure if this is caused by maximizing a specific Tool or Meter Window, or if it is dependent on a specific docking position of a Tab Group window. … Doing some quick tests it is most likely connected to the docking position.
Changing the Workspace Layout will not recover the missing interface elements.
I see now. This is a bug indeed.
This will be fixed in WaveLab 13.0.30