Man.... How can they mess up on something so small...
I'm still using DSight 2017 and I don't really use it to draft. I merely use it as a viewer so I've never encountered the problem you have. Regardless, it is both astounding and disappointing that an easy bug like this get released if the bug is indeed a bug for most people and not just you.
It may be system specific as our Var is not having this issue with the same version. Quite odd indeed.
The only bug I've had similar is one where I'd have a circle appear in the middle of my screen while zooming. It didn't happen on every file so I never reported it. Though, I'll give you the headlines I'd give anyone.
Have you tried reinstalling?
Have you checked your graphic card driver?
Are you using a 32bit version of draftsight on a 64 bit computer?
Have you tried running DraftSight as Administrator?
Good luck with your problem.