If you do not see (some of) your events in version 2, there is probably some corrupted data in your Android calendar data.

If you use cloud data, try resetting the Android Calendar storage.

If you use local data with no sync or backup (you really shoulnd't especially on a mobile device), for now best go back to aCalendar 1.17, you can find the APK here: http://tapirapps.de/apk/ 

You may need to uninstall the 2.0 version first.