Dashboard refresh

Dashboard tiles maintain all of the filter context in place at the time of pinning. If you pinned a visual after applying filters in the report, whatever filters were active when you pinned remain active on the dasbhoard. If you had filtered to a specific week, for example, the dashboard tile will always show data for just that week.

I do not know if this is precisely the issue you're seeing, but it is a common point of confusion for dashboard functionality.