When clicking to next month it is on only working for the next month ie. from October to November, but clicking to December you need to click the cursor somewhere else and come back with the mouse to the next month icon (>) to go to the next month again. Previous months is working just fine. See link for video.
I have noticed that if you click too quickly, it will fail to move the calendar. Slower clicking works just fine.
yes indeed. I work quite fast when processing mails and appointments. 
So clicking fast is not a good option for changing months. Maybe they can change this in the next version.
Thanks for this comment