Latest version (Glyphs 3.2 (3169))
While exporting a font, there’s an Export Result window, with hundreds of messages such as:
Anchor "anchor 582 686" for base glyph ... overrides previous rule. Found in feature 'mark'.
I don’t know what it means or how to fix it. There are no anchors in most of these glyphs.
It has started appearing as of this 3169 update.
It might be connected with this newly-reported error, but it’s a bit more specific.