Date of Birth issue - join window disappears

I am using the Evo template with 7.2.1 and when I go to enter the date of birth, the calendar popup appears as it should, but when I click on the dropdown for the year, the join window disappears and I have to click on the join button again.

Is anyone else experiencing this?

This problem is already reported and fixed:

https://github.com/boonex/dolphin.pro/issues/188