Hello @Krzysztof_Gryzka,
The Brush Modifier still controls the radial resolution of the tube. The farther the value is from zero, the more points there will be. The number of points = the point value/2. So a value of .10= 5 points, .20=10 points, .40=20 points, etc.
Technical support for ZBrush is not provided on the community Usage Questions forum. If you believe you have a have a bug or technical issue, or would like to make a feature request, please go to Pixologic Support and start a conversation there. Reporting these any place else may cause your issues to be missed!
Thank you!