Detail lines in legends, keep showing as thin even though thin lines is off.

[Niko221q]

As you can see on the screenshot the blue around the line, is supposed to be the thickness but when I'm not hovering over the line, it's displaying as thin.

Any ideas at all? I've never seen this and I'm so lost..

Any help at all would mean a lot!

[Niko221q · Accepted solution]

So apprently when using "offset" tool, the problem just vanished...