Change class name in kerning panel

I just can’t do it. One dialog appears that asks me if I want to change or rename, both do nothing.
Please help.

To contextualize:
I had a kerning group named ‘g’ and I want to call it ‘u’ now so it matches other file with which I will interpolate, so the kern classes need the same name.

Thanks

What version of Glyphs do you have? That might be fixed in the latest cutting edge version.

I have the latest stable version. I normally don’t install cutting edge versions. But I can if that fixes it. I’ll let you know

It doesn’t work on version 2.4b (933)

You are right. I did though that I had fixed this. Not it works.