Hey Tim —
Is there a special reason that the RMX Scaler wipes all layers as it writes the new rmx’d version in? It seems to me to be more intuitive to be able to remix, create new master layer[s] and then regenerate from a source for a compare and contrast. Could values be stored on a layer level as opposed to glyph? Copying and pasting values back and forth can be a bit… slow.
Also I just realised why something wasn’t rmx-ing - I had a brace layer. Would it not make sense to remix the masters any way and allow a re-interpolate and fix natively in Glyphs? Otherwise it makes sense to me to have an additional set of values for said brace layer in the RMX Scaler. At the moment it’s error trapping for no good reason I see.