Type of a variable is changing

Hi, everyone!

  1. I successfully added a variable with "Date" type and a filter in a query:

  1. But I cannot connect it with a dashboard filter as I don't have a varible with type "date":

  1. And when I went back to the query, variable type changed to "Text" type:

Is it a bug?

what is "date range" filter type?

Type of "Date Range":

May be I should use "Single date"?