Just played a bit with my scanner. Seems that Paperwork 1.3.x seems not to understand the TIFF files (multi or single page) that it creates. OTOH, when I import JPEGs it seems to work, with the irritating extra work of selecting all pages manually 
Not sure about the 1.99 (and if I should use the flatpak or simply go with the virtualenv, even if a Makefile in the top directory of a supposed Python project looks odd 
).
Another thing that I’ve observed with the 1.3.x flatpak (not sure if it’s 1.3.x or the flatpak integration?), sometimes the GUI looses document sidebar directory, e.g. it happened to me twice after I deleted a document.
Thanks,
Andreas