Sometimes the problem is due to a MacOS bug

[support]

You can observe visual glitches in our software, under Sierra (20 of september 2016).
You can see the same visual glitches, in the Finder of Sierra.

This is a bug of MacOS Sierra.

[support]

Problem fixed with MacOS Sierra update 10.12.1 deployed on October 24th (more than 4 weeks later).