Pressing TAB key in application affects ComboBox selection

[NavCore]

I'm using MetroModernUI v1.4.0 in my WinForms project.

Wherever I press TAB key in the application, all MetroModernUI comboboxes becomes selected (blue) and that behaviour stays like that until I don't restart the application.
The only way I've manage to revert blue comboboxes to default behaviour is to press ALT key and close/open combobox. By doing that, all comboboxes resets somehow and app behaves normal until the application is restarted and we got endless TAB-behaviour loop again :)

Very strange, and I don't have any idea how to prevent this behaviour globally for all MetroModernUI comboboxes.
Can you please help me solve this problem....

Thanks in advanced,
Josip