Alt+MMB issue

In Rhinoceros 7, viewing from top view, I use the alt+mmb to switch to isometric view, The command is smooth while holding the alt key, it works also with the right mouse button without the alt key.
Both commands work.
In Rhinoceros 8, while holding the alt key+mmb the view rotation is performed well at the beginning but continuing to orbit, the view rotation starts to hang/stutter, it’s like two key/mouse commands are interfering to each other.

Edit:
switching from comma to dot fixed the problem.

Edit2:
No, it doesn’t…