Updated August 31, 2018
DPA has a Blocked Sessions metric in the Resources > Sessions tab for SQL Server and Azure. Because of the differences described below, there are sometimes differences between the data shown by the Blocked Sessions metric and the data reported by DPA's wait time monitoring.
The Blocked Sessions metric shows the number of blocked sessions, including sessions that are normally excluded from DPA’s wait time monitoring (for example, sessions doing backups and restores).
Also, the Blocked Sessions metric runs every 60 seconds by default, so it reports the sessions that are blocked at each 60-second mark. In contrast, DPA’s wait time monitoring runs more frequently.