I don't currently have a 7.3.9 AMP, but to get you a quicker response:
On AMP 7.6.1, Reports -> Device Uptime report
Filter by device type -> select controllers, this includes master/standalone, local, standby, and virtual controllers
Choose the option to 'include details about every device'
Then enable the setting 'limit to devices with downtime' - this flag only affects data displayed in a table, not graphs
You can set your report start and end time to a smaller window, I gave it a 10 minute window
Alternatively, you can choose the 'custom report' and only add the 'device uptime' -> 'uptime by device' portion.
This report may or may not have been available in 7.3.9, but it's definitely there for 7.6.1 (7.6.2 to be released next week).