Hi,
I found a difference between Glyphs 3 and Glyphs 4 when adding a corner component to a monoline stroke.
In Glyphs 3, I can add _corner.stem to the corner/extra node of the stroke, and the corner component is generated correctly.

In Glyphs 4, using the same setup and the same corner component, a red circle appears at the target point and the corner component is not generated.

I can reproduce this in a minimal test font. I tested this in Glyphs 4.1.1 (4108), launched in Disable Plug-ins mode.
I have attached the minimal .glyphs source file used for this test.
corner_components.glyphs (9.0 KB)
Could you please let me know whether there is a workaround? If not, could this be fixed in Glyphs 4?
Thank you!
An update:
You may already be aware of this, but a similar issue occurs when adding cap components to open stroked paths with pen points in Glyphs 4.2 (4200). Immediately after adding the cap, it sometimes appears only in the preview, but disappears after saving and reopening the file.
Both corner and cap components worked in Glyphs 4 up to and including build 4004. However, I’d prefer to keep using the latest version rather than downgrade solely to work around this issue.
In I.001 in the attached corner_components.glyphs, saving after adding the corner component stores the _corner.stem hint without an origin entry:
{
name = _corner.stem;
type = Corner;
}
Separate cap tests in 4200 showed the same missing origin entry. Setting originNode through the scripting API also did not persist after the layer updated.
I also tested build 4004. After reassigning _corner.stem in I.001 through the scripting API, both originNode and the attachment reference in the saved file were retained after saving and reopening. The corner also displayed correctly in the Edit view. The saved hint contained:
{
name = _corner.stem;
origin = (0,1);
stem = 1004;
type = Corner;
}
I hope this information helps narrow down any changes in how attachment references are handled.
Thank you for your continued help.