Hi Thomas, the date filter on the dashboard is “universal” in a sense that it can work for different date dimensions at the same time.
You can actually define a date dimension it should work with for each of the visualizations on the dashboard. You can do this in the “Configuration” section under the “filter by Date Range as” option.
If you do not do this, I believe it selects one of them by some rule - I think the highest priority has potential date filter used in that visualization. If there is none, then it selects one of the ones that are compatible from the LDM perspective for the metrics used. I am not sure about the exact logic there, if it is just “first available” or if it also takes into account usage of other filters.