Some other override is in place. Maybe Phase Filter Graphic Override. Set Phase Filter to Show Complete.
Wait a minute. What are we talking about in your screenshot? That thick black line at the corner return? What is it? Wall end?
...You didn't by chance use the LW tool on that line; did you?
Just in case you are unfamiliar with the Linework Tool (maybe someone else modified that line), it's located on the Modify Tab.
Cut Line Style? How were you able to get Cut Line Style to affect only that one wall end? Or were you not talking about that thick black line at the upper-left corner?
Okay, I get what's going on now. The Projection Line Weight is greater than the Cut Line Weight.
You can also correct by making Projection and Cut the same weight.