TrueType delta instructions below 10 px?

I’m adding some delta instructions to a font and noticed some strange behavior. I’d like to improve the position for the A bar at 9 and 10 pixels. When I add a delta at 9 px it works fine. However, when I add a delta at 10 px, the 9 px one stops working. Is this a bug or am I using deltas wrong?

deltas

What version of Glyphs do you have. Where did you test? Can you send me the .glyphs and the test file?

I’m using Glyphs 1176 and testing in Opera 56 running under Windows 7. For now, I’m only using the preview address generated by Glyphs. I’ve sent the file to support.

Thanks for the report. I fixed it.