When using “offset filter” in G4, I added a few units to the weight and had the “Keep Compatible” box checked, but G4 added several points to several outlines anyway.
Can you send me an example?
I fixed all the added nodes by now. Maybe I can redo it for you? What format woud be best for you? Screenshot?
This is an inflection point. For proper “s” curves it is difficult to make a good offset without adding a node. When it is almost flat, it could do without. But deciding that per master is a source of incompatibility. So “keep compatible” doesn’t mean that it will not add points. But that it tries to do so the same for all masters.
That is just the problem. The other masters don’t have the extra points. Is this a hard thing to fix? It never happened in G3, to me.
Then the other masters don’t have that inflections? Could you send me a shape that has the problem in on master and not in the other but correctly works in Glyphs 3?
can you send me the file with those to shapes?
hat is an segment with an inflection, a very sublet one but an inflection nevertheless. I’m working on those very shallow curves at the moment …
Please use the “Show Angled Handles” plugin. It will highlight all these kind of issues for you 
Yes, very subtle. It is very small sups glyph so not much room either.
I hope you can resolve this. Adding unhelpful points in close proximity has its own set of problems