Export Error Glyphs 4

I get this Message when exporting static fonts cff/otf with remove overlap and Autohint selected, Glyphs 4 [4001], what can I do about it?
The same file used to export just fine in Glyphs 3, and the respective roman file exports without problems in Glyphs 4.

Could you send me that file?

The hints in at.ss12 are unusable. Remove or fix them. And I fixed the code that those hints are not messing up the export.

Thanks Georg,
the file exports fine now.