Instructure has acknowledged a known issue which limits sub-account administrators from utilizing some Admin Tools functionality.
On Feb. 15, 2018, the Learn@UW Madison team was informed by Instructure support that sub-account administrators are unable to successfully run the Course Activity report within the Admin Tools feature (this is the functionality within the "Logging" tab of Admin Tools). They should be able to use the other Admin Tools functions.
Instructure is planning to deliver a fix for this in a future release and will communicate it in the Canvas Community Release Notes.
In the meantime, please contact firstname.lastname@example.org if you're a sub-account admin who would like a report run for you. The Learn@UW Madison team can manually generate these on request.