I remember that before upgrading from 16.04 to 20.04 I used to be able to drag and drop across applications that are each in full screen, by using the application switching mechanism (Alt-tabbing), or by temporary hovering over the icon of a running application which would then get the focus.
In 20.04 I tried both means, in addition to attempting to switch directly to the desired target application by pressing Super+num, but to no avail.
It seems that all application switching mechanisms get disabled while a drag is in progress.
Is there a way to make that work? Or to practically achieve the same result in a usable way? Are any related bugs pending?
Question #37335 seems to be a similar or related.