Kivy cursor black background

Question

I am using Kivy with python for my app. But there is black background on my cursor on Kivy window.

How can I fix it ?

I am using python3 on OSX

UPDATE

I have same issue with hello world application too.

When mouse stays at same position about 10 seconds, black background disappears, but when leaving and entering again, same problem occures

Answer 1

After many retries I figured out the problem. As @Mikhail Gerasimov said, it was thread issue. H had lot of calculations in main thread (it takes over 10s).

After moving it to another thread, and let main thread empty, the problem with black background fixed.

Also I moved Kivy updates to another thread