The spacing between instances is completely off in the preview – even though the two masters are correct. This occurs in all previews, regardless of sidebearing. Any ideas for a fix?
Brace layer? Or stray point?
I don’t have any brace layers, and checked with your script for stray points (remove stray point), still not displaying correctly.
Same phenomenon in other glyphs as well?
Yep, in all of them, as far as I can see.
Can you please send me the .glyphs file to support (at) (this website without ‘www’ or ‘forum’). I will have a look.
I fixed that yesterday.
I’m on the cutting edge update, is there anything else I can do to get the normal view back 
I need to upload a new version. I’ll do that soon.
I know there has been no new version since your last post, but is there any other way to fix this problem? It seems like the instance kerning is also corrupted on export the same way as the previews are