Handling blank dates in dataset

[Demonkratiy]

Issue from customer:
It seems that issue is, when some events do not have the date and Calendar visual itself does not filter those items. When filter for calendar is applied (date IS NOT 0) then it works.

Note: in such case seems that some event can be rendered on the visual but it can't select some events on other visuals as there are no date for such event. User want to handle this somehow.