I _just_ ran into this rather frustrating change in #FreeCAD defaults that has arrived in 1.1. If you run into weird 'wire is not closed' issues if you're importing external geometry, either _manually_ make it construction geometry, or if you never want to think about this again and just want the old default back, go to 'Edit', 'Preferences', 'Sketcher', 'Always add external geometry as construction'.

No idea _why_ this behaviour needed to change, but here we are.

https://www.youtube.com/watch?v=fstXygscASo