darktable 2.4.4 - print module problems (not only .raf but also other types)

180917: more clues added below

Problem
darktable’s print module does not accept images when they are opened from within darktable. Odd widht/height values are reported:

Screenshot%20from%202018-09-16%2021-12-38

Setup
Linux Mint 19 Tara, Cinnamon flavour ('buntu Bionic)
darktable 2.4.4 pmjdebruijn ppa
GIMP_AppImage-git-2.10.7-withplugins-20180913-x86_64
Raw images: raf from X-T1, cr2 from Canon and other raw types (will investigate more).

Clues
Problem does not appear if I right-click a raw file and select Open with/Darktable.
Problem does not appear when The Gimp sends a raw file to darktable for processing.
It only seems to exist when an image is opened/selected in the lighttable module.

Could someone please assist?

Sincerely,
Claes in Lund, Sweden