Strange issue with strokes

I have a stroke width applied to my paths, but when I move the points around, the counter spontaneously fills itself:

The same issue happens when run Offset Stroke on the paths. The corner nodes also seem to glitch out.

Glyphs 3.2 Latest Build, macOS 12.4, Plugins disabled mode

That is an edge case of the outside corners. Select the leftmost point, right-click and choose Open Corner.

Thank @mekkablue , I tried this however the problem still persists

Add an extra node like this:

Thanks @GeorgSeifert that solved the issue. I am wondering, is this the expected way to handle this issue, or is it a bug & this method is just a workaround?

As mekkablue mentioned, this is a side effect for the outside open corners. The four is one of the very few places where it fails so needing that hack in this case is hopefully OK.

Ah, I understand now, thanks!