Yes indeed, with Qt the manifestation is a bit different: the text is displayed in the terminal when the the menu is clicked, but you still need to hit the return key for Octave to show the prompt.

Marking the bug as confirmed, even though mainly with fltk.

The following example shows the issue:

fcn = @() disp ("toto")
figure ();
uimenu ("label", "toto", "callback", fcn)

Clicking on the menu doesn't trigger the execution of the callback, or at least the expected "toto" is not printed onscreen. The only way I could find is to click in the terminal and press RETURN.