In Q1 2015 we released grouping and virtualization functionality in whole DropDownList family (AutoComplete, ComboBox, DropDownList and MultiSelect), which force us to re-write whole widgets. This major overhaul was required as some of the current behaviors were not compatible with the new features.
Because of this major re-write, some bugs/issues were slipped in the official release (logged here).
With regards to the depicted issues, all of them are resolved and the next internal build that will be public later this week, will include all fixes.
Please excuse us for the caused inconvenience.