No selection shown in the preview window (premiere pro beta)

Hey everyone,

I have a problem with the newest version of Premiere Pro (Beta).

When Premiere is opened on my main monitor (2560x1440px), no selections will be shown (no blue lines, ...).
For example: When drawing a mask, shape or when cropping something, it's not visible in the preview-window (you have to guess where it is):

But when using premiere on my other monitor (1080x1920px) the tools are visible like usual. So you see the e.g. mask selection (blue line):

If you have some idea how to fix the problem, I would be really thankful!

Have a nice day!