This is working as designed but is very confusing.
In my demo I have a dummy account and they have 6 entries but only 4 reporting category types (meeting, call, update, email)
When I pull a report on Activity Timeline I get 6 results as expected and they all show, I can also filter for email and get the two results as expected.
However, when you have a scorecard mass edit report and try to do the same you get a different result.
I know this is expected per the talks I have had with internal sources because its pulling accounts that HAVE at least one entry with that reporting category.
However, this is not consistent with normal reporting nor documented anywhere.
I would like to either add this to documentation or make the filtering on mass edit the same as a normal report where it looks for the record and not the account as a whole.