To me this is a bug because of how annoying it is for my use, but since it is not necessarily something that is not working as designed I'll post it as a VERY BIG WISH, as it renders calendar and agenda views useless for me.
Given multiple documents and a calendar view
When you navigate in any of the documents either to the lower levels of the outline or you filter the calendar view
Then the correct items from the current document are displayed and filtered correclty,
BUT the items from all other documents are displayed as well!!!!
This is annoying and makes the calendar view so cluttered that it's almost unusable.

Calendar views should behave as any other view (display only what lies in the place in outline where you are positioning the pane in). In my case it might be that the items being brought into the calendar view are from the calendars associated to my email accounts. If that is the case then I would like a way to filter them out when I don't want to see them (which is most of the time). I know that in Settings there is away to select/deselect individual calendars from ever displaying in Legend, but that is not what I want. I want th eability to select on a per calendar view what calendars I want to draw info from. e.g. in my Personal Weekly Caendar pane I want to see the birthdays I have in my gmail calendar, but in my Work Weekly calendar I don't want to see any of that.

We've had some discussion about this in slack https://moodo.slack.com/archives/C99CWQ484/p1621542269016900, so for people like @Jerud that want all encompassing calendar views that consolidate all documents (which is a valid use case) there should be a placeholder in the outline overview that acts like a root level (and placing yourself at that root then shows everything in its sub branches...i.e. all documents).

In general I think any view (calendar, agenda) that can aggregate items from multiple docs should provide a way the user can indicate what documents (s)he wants to draw items from (and by default it could be enabled by only the current document).