I am happy to report that with the most recent Mac OS update (10.13.5 Beta (17F45c)) this bug has been resolved. The new Beta version was released 21-Apr-2018.

Hi Alexander, I forgot to tell you how much I LOVE your app - thank you very much for all your hard work!

I can't save a screen image. When I use CMD+SHIFT+4 to select a screen section, the cursor goes away as it does on all apps. Anyway, I'll let you know if this issue resolves itself with the next beta release.