Variable Font Export Error 842

I’m unable to export a variable font. OTF exports successfully. Any help would be much appreciated! This is the error I get:
“There was a problem writing the file. 842 -[OTTableWriter getOverflowErrorRecord:]”

BTW - I’M running Glyphs version 2.6.1

Try the latest beta please. Go to Glyphs > Preferences > Updates, activate both checkboxes and press the Update button.

Thanks for the response. Unfortunately the error persists.

Can you send me the .glyphs file.