After Ubuntu stock dist upgrade from 18.04 to 20.04 and upgrade Gimp from 2.8 to 2.10 I can't open an image with Gimp in the same instance.
Simple call
$> gimp ./1.png
Or my bindsym
bindsym --release Print exec --no-startup-id "A=$(date +%s%N | cut -b1-13) && import -window root /raid/user/tmp/0images/$A.png && gimp /raid/user/tmp/0images/$A.png"$
I tried flatpak with the same result
$> flatpak run org.gimp.GIMP
In another case Gimp 2.8 works fine for all of this.
I didn't try Gimp 2.10 for Ubuntu 18.04.
The system: Ubuntu 20.04, Gimp GIMP 2.10.20, i3 4.19