as you can read in
https://bugs.scribus.net/view.php?id=15427groups are not implemented "correctly" in 1.4.
so, if it works in 1.5 i'm not sure it should be fixed in 1.4, since it might be lot of effort put in a legacy version... and since the scribus workforce is very limited, i would prefer the team to focus on the development version!
... and i really see few cases where somebody would want a group with some items printable and some not... : - )
but i made a try with 1.4 :
- three shapes in a .sla.
- one of them set to not to be exported.
- group them.
- it shows correctly in the preview (view > preview mode): one of three shapes "missing".
- it exports correctly in a pdf : one of three shapes "missing".
then i tried your file: i see the issue...
it seems to happen with text frames and not with shapes...