Hi, I’m new here and wonder(if I’m not mistaken) why Glyphs does not produce separate undo/redo steps for each layer/master? If it has to be enabled somehow, please let me know. Thank you.
This is not a functionality in Glyphs. Undo is for each glyph and doesn’t discern between masters.
I advise making use of 1. the background layer for every layer and 2. backup layers (simply duplicate the current layer in the layers list on the right to keep a snapshot).
Otherwise, of course, a git workflow rules supreme (with glyphspackage file format), but that’s for more overarching undo.
This question was asked on the forum before.
The short answer: it would be quite tricky. E.g. you do changes on on layer. Then you change a property on the glyph itself (e.g. a kerning group) and then you change something on a different layer. So how to undo the change on the glyph now?
thank you, I’ll try background and backup layer 
i got your point and understand the complexities, it’s just the way i deal with layers in fontforge and it’s handy for me. thank you.
Would it be possible to switch to the layer which changes when you click undo? Now, if undo affects some other layer, you’re basically blind guessing and have to go through layers to find changes, which may be hard to spot and so on.
That is on my list. But quite tricky as the undo is quite opaque in its inner workings.