"Instance as Master" adds duplicate paths in intermediate layers

Glyphs
1

Hello, I am unsure as to why this issue arises, as it only happens with specific instances.
I have a file ranging from Thin(20) to Black(220) and Compressed(50) to Extended(150). Four width masters per three weight masters per two italic masters. When I add the instance Thin SemiCond (20,85,0) as a master (in order to have a variable font origin for a subset variable font), I encounter the following problem in intermediate layers:

image
image1354×2278 180 KB

The intermediate is inserted with the axis rule wdth<85, which is exactly the coordinate of my variable font origin master. Does this have anything to do with it? Adding instances with larger width works fine.

2

I would STRONLY discourage on having condition breakpoints near instance (or masters). There are rounding issues (is that range inclusive?).

And the user could be confused: e.g. you have a condition at the Regular on the weight axis. The user select the Regular and then decides he needs a tiny bit heavier font (for smaller text). But he not only gets more wight but also different shapes.