Multiselect dropdown's Document

Combining Multiselect dropdown & DropDown
I’d like to filter it out.

①Multiselect dropdown – Trip name
ex . Japan, Hawaii, China and Canada.
②DropDown – Class choise
ex.Economy,Business,First Class

In combination with.
I want the target list to appear on the screen.

However, in that case
When I filter the list, the form “Input” and “Select” appear as options, but the “DropDown” option doesn’t show up.
2020-08-25_19h44_38