Zoom windows appear as gray boxes

When sharing a screen, the Zoom windows, such as video panel and floating meeting controls, appear as gray boxes. They are still visible in the screen share even if the Show Zoom Windows when Screen Sharing feature is turned OFF. A month ago they were "invisibe" to my students, this bug has started on the latest version 6.3.5 (54827).

Is there a way it can be fixed and become "invisible" again?