wayland drag&drop should work

i started gnome like described on the arch wiki, setting QT_QPA_PLATFORM=wayland:
https://wiki.archlinux.org/index.php/GNOME#Wayland_sessions

• then i started nemo, and avidemux. dragging a file from nemo into avidemux does not work.
• then i started dolphin. dragging a file from nemo into dolphin does not work.
• dragging a file from dolphin into avidemux does not work.

to verify, i started X as described here:
https://wiki.archlinux.org/index.php/GNOME#Xorg_sessions
and all of the above works.

i am very unsure what is responsible for this, but as fedora supports gnome and wayland, my first guess was that QT might be the one responsible.