When I copy paste from FLS I get this problem very often:
https://www.dropbox.com/s/o3q7nhhizig40fl/Glyphs_curve_errors.png?dl=0
Is this a known bug and is there a workaround? Sometimes it works to change path direction. But if you than add another point it happens again.
can you send me the .vfb that causes this and a screenshot what you have selected in FLS when you copy?
Looks like there is a TrueType curve in the FontLab glyph.
I converted all the glyphs to Postscript in FLS before I started copying them.
Just to be sure I tested it again, and this is the result (left):
https://www.dropbox.com/s/hynfpxyaomvaxef/Glyphs_curve_errors_2.png?dl=0
Can you send me the .vfb?
And you know that you can export the hole file from FLS to Glyphs? http://www.glyphsapp.com/tutorials/importing-existing-fonts
The file is in the mail. It’s the same as yesterday though. 
I’m gonna try to export the old FLS file right away. I started just testing some options, but realize now that I’m far enough to do it the right way. Makes sense to prevent more errors.