What could be wrong with Feature code in imported file

I have exported FontLab 5 fonts and successfully brought them into Glyphs, except that when I try to compile the OpenType code, I get the singularly unhelpful

The operation could not be completed.
No other information is available about the problem.

Could the fact that the font includes double-encoded glyphs be the issue? If not that, what are other likely culprits? It has pretty complicated classes and features, but I’m not spotting any obvious errors.

Can you send me the file?


The font is saved in an unusual format. The code path hat reads it has a bug that reads some wrong values that cause the export to fail. Save the file once and reopen it should fix it. And I fixed that issue for next time.

Thanks so much for the help!