Why there is blank day filter while I don't have any data with blank date

[NoobAnalyst01]

Hi,

I have a dataset only have two column dispatch date and truck number which contains today and yesterday' data. But when I put a filter beside, beside those tow date, I have a blank date option, but I don't have any data with blank date, anyone knows why this is happened?

Thanks

[nirvana_moksh]

Is this table the result of any UNION or is it a single independent table with zero blank values with date?