Pattern brush preview problem
Hello everybody!
I have a problem that I can not solve. I created a simple pattern brush in illustrator. Brush works fine but after saving the file and reopening it preview box in brush menu is blank white box. Brush is working fine. If I replace the brush ornament it becomes visible but after saving and reopening it is gone again.

Here is also link to the file with problematic brush.
https://drive.google.com/open?id=1BoYdHe2zLcj13fCYjNpEaSNrhxi6upJ8
