why in line 6 when I offset,
the line is broken like that???
If you can share the file with the original curve, someone may be able to figure it out.
Remove the bad one and try again, works fine for me.
As @Box, I was able to delete the incorrect curve and then to offset 300mm (repeared clicks on the inner face) about 25 times without any problems. I thought that would be enough.
I have no idea what happened to your file.
you can send back the file? (after repaired)
I’ve try,
not work 