No Op, but I am having the same issue. I can confirm that the "Opening and saving files" and check that the "Default behavior when opening a project file" is not set to "Always import models", but set to "Always ask me this", but I also tried "Always open as a project" and it still does not import or ask to import settings. I USE TO HAVE the setting at "Always import models", but changed it and restarted cura.
Windows 10
Ender 3
Cura 5.0.0 ( and also Cura 5.1.0 Beta + 304 )
Using CHEP's just released profiles for 5.0 link - > https://thangs.com/designer/CHEP/3d-model/Cura V5.0 Good (0.20) Profile from Filament Friday-184723
I will also attach it here.
stderr.log file attached.
EDIT: Help on FB suggested it may be the Start-up Optimizer causing issues, and when I disabled it, I was able to import the 3mf as a project.
So, is this a Start-up Optimizer issue, Cura importer issue, or user error?
FFV5.0-Good-020.3mf Cura5-3mf_Load--stderr.log