Filter doesn't work when no data in a cell - xamGrid


Please look at the attached project.

I'm trying to filter "Level" column but receiving an error. I need to have cells without any data and should be able to filter them. Also I generate columns dynamically and column keys are different only by the index.

Any help to make the filter working correctly, please?


For example, I expect the following behavior:

Click on Filter at first "Level" column and see 2 available options: User and "Empty" string

Thank you