A friend of mine showed me this font he was working on and he was trying to add handles to it to change the form. He couldn’t add more handles to some of the paths for unknown reasons. I suggested that he change it between quadratic and cubic and tidy up paths was used to try to change the path. I looked at the file and found this floating point that isn’t referenced anywhere in the manual. When tidy up paths is used here it crashes Glyphs. I cant share the file unfortunately but does anyone know what kind of path this is and why it wont let him add more points. Furthermore, the end of this little middle handle segment can be moved and the end point follows it. You can suggest redoing the form and making a new one. But he said this was happening just as he was working through the font.
It seems that the path is corrupted. Would it be possible to send the file if you remove all other glyphs and maybe all other path segments from that layer?