iOS Mail App (iOS 13.2.3) does not forward emails

Sorry, I provided misleading information above.

Indeed I get to the same state indicated by your screenshot above. And indeed, if I press “Forward”, the app minimizes as yours does. Pressing other options works normally. And forwarding from within the specific message to be forwarded works normally as well. But the behavior you describe fails for me as well.

RiderPride wrote:

From "All Inboxes" long press on an email does not forward.

It works just fine for me. (iPhone 11 Pro, iOS 13.2.3.)