Open /xwiki/bin/view/Main/AllDocs?useLiveData=true and try to filter by date:
- if you filter from the table header you get a date picker instead of a date range picker, which is useless
- if you add the filter from the Advanced Filter panel, then the filter operator is set to "Is between" and a date range picker is used as expected, but the default value is set to "1970/01/01 02:00" which is strange. It should have no value set by default.
- If you select a date range from the picker you get "Invalid date" as value. Same if you select from the predefined values like "Last 7 days"
- if you select the Contains operator then you get a date picker, which makes me think that the filter from the table header uses the wrong operator by default. In any case, using the date picker for contains doesn't make sense. It would have made sense for equals, but for contains it should leave a plain text input so you can type whatever you want (a year, a day, a month, any part of a date).