RMX for Glyphs 2 'live' preview not working

I’m using Glyphs 2 (latest update) and the latest RMX filter update. In write/edit view, I select a bunch of glyphs, let’s say, A-Z uppercase and a-z lowercase, only glyphs containing paths, no diacritics or components, of course. When I run RMX Tuner on all of these glyphs and try to make the changes, although I can of course change the numbers/increments, I get no live preview. It used to give me live preview, now not anymore. Of course my ‘preview box’ is checked. What could be the problem?

Anyone knows what may be the problem? @TimAhrens ?