When adding a TTZone the brown glyph box from metrics and alignment zones is not drawed correctly (in the TT instruction tools) See image.
I assume Glyphs is drawing from the first to the last zone in the list but in the custom parameter floating window is not possible to rearange zones.
Can you check the dialog in the first master (or the master that that is set as the source for the hints)?
And can you send me the .glyphs file?
Now I understand. I’ll have a look. Thanks.