Resolved Errors still showing in "Active" Tab

We have gone though and cleared many errors by marking them as Resolved. When we then go to the dashboard page the Active count shows the correct Active of 20, however, if I click the More button it begins to show me the errors we have already flagged as Resolved. Although the Active count still shows 20.

As we performed an upgrade on a live system yesterday, and received many faults in one day, this is confusing us as we have to keep rechecking errors to see if one of the team has resolved it or not.

Thanks

---