The Issue from freeze of composite columns

Is this issue fixed already or is it still remaining?
Is there other way to solve this problem?

We are still not sure how to implement such functionality - if you have any ideas we accept pull requests.

I need the checkbox filter to show all available data but I can only see the values which are in current page of data grid.
One more, does radzen support showing date range picker for filter date columns?

Use LoadColumnFilterData similar to this demo:

The default filter mode allows that: