Hi,
thank you for the answer.
I have looked at your example and, to tell the truth it is abolutely like my app... and actually it has the same issue.
But.....
I was trying both your example and my app in a standard android emulator...
trying them on a real smartphone does not reveal any issue, the indeterminate progress bar acts as expected.
I don't know why... but that's it.
I report this hoping it is of your interest or that it will help other developers.
Thank you very much