ComboBox forgets selection when clicked out of focus

I have a set of combo boxes that show a product based on the selected criteria. When I click out of focus after selecting a menu, the last selection is forgotten. Is there a remedy?

after selecting a menu
The option can be selected by
- direct mouse clicking
- selecting option value from list by keys and pressing enter key
- typing full option name and moving focus out of control

All 3 use-case works correctly in local samples.
If you have some specific scenario in which problem occurs - please provide more details, so we will be able to reconstruct issue.