No arrows for errors when using Part Checker

Hi there

I'm having trouble with the Part Checker in Direct/Express as I can't get the arrows and labels to point to the errors in the viewport.

I have a part which I know contains errors. I click of Check Part in the ribbon and then select the part. I have all of the check boxes ticked (i.e.keep labels, etc). When I execute, I get a text alert in the log that lists 10 errors but the viewport doesn't have the arrows and labels pointing to the offending edges. I can see tiny tiny orange strokes where I believe the errors are but nothing else.

What am I doing wrong?

In the past I know I have opened the part and the arrows and labels show on startup so know it works but can't replicate it when I need it. Any tips?

Thanks..