Ok, finally I had the time to test your observations. And yes, I can confirm that changing the font to Noto Sans cures the problem. I tried the following fonts as "General Font": Good: - Nobile 9 - Noto Sans 9 Bad: - Arial 9 - Droid Sans 9 - Liberation Sans 9 It seems, that primarily fonts are causing the problem, that look more condensed, while fonts looking wider are working without causing problems. Sadly I better like the more condensed ones.