For me, "LC_ALL=C scribus" also fixes the problem, but does not affect the program's GUI-Language (German in my case).
I suggest that the Ubuntu package maintainers fix the K-Menu / Gnome-Menu entries for Scribus to e.g. "LC_ALL=C scribus-ng %f". This way, the problem is fixed for every user for now.
For me, "LC_ALL=C scribus" also fixes the problem, but does not affect the program's GUI-Language (German in my case).
I suggest that the Ubuntu package maintainers fix the K-Menu / Gnome-Menu entries for Scribus to e.g. "LC_ALL=C scribus-ng %f". This way, the problem is fixed for every user for now.