Line weights displaying incorrectly / inconsistently. What's going on?

I am working with an asset library I did not create, and running into an issue where some of the line weights are not displaying as they should.

I took some screen shots as an example. I built the star from scratch so I know it is displaying correctly with a 6pt stroke.

The asset to the right (3 lines), however, is having the issue I'm asking about.

As you can see, they initially look to be almost the same stroke weight, but upon further inspection you'll see that the star has a 6pt stroke while the lines have 1.897pt stroke. Why are they displaying so closely?

And here you can see what happens when I change the stroke weight on the 3 lines to "match" the star icon at 6pt. As you can see, they do not match. How can I fix this?

Thanks in advance