There's a known issue with the Summary Row feature in Data Studio where it will report the first result given back by the Supermetrics connector rather than the total values for each column if you set a filter on the table. This is because Data Studio doesn't report back if the results should be filtered for the summary row. As it's a Data Studio behavior, there's nothing Supermetrics can do about it. You unfortunately have to choose between getting the summary row with no filter applied or using the filter on the table without the summary row.
A affected user has reported this issue to Google, so please go here and star/contribute to the conversation to let them know this is an impacting issue:https://issuetracker.google.com/issues/77944627