Thanks for your response, Paul. I wound up running the Outcome Results report and was able to determine which courses were using Outcomes for assessment based on the information present in that report, so that's a really helpful idea. I was hoping to get a visual alongside the info; the Admin Analytics tool is really neat and I had hoped it could easily present the info I was looking for!
Outcomes are written as Course Level Outcomes (stated in our Course Catalog as determined by Dept. Leads), are preset at the admin/root level in Canvas, and then instructors are expected to attach them to rubrics of their own design. Not all rubrics track an Outcome (as not all graded material is necessarily course outcome driven -- thinking probes for understanding, some reading reflections, those sorts of things), but Outcomes are only ever to be present and assessed within a rubric, if that process makes sense.
We've been sort of building the airplane while flying it with this process, but have, up until this term, had a pretty smooth process for tracking these Outcomes at the course level. I checked two instructors against each other, one that was present on the list of those using Outcomes according to the data in Admin Analytics, and the one that I mentioned in my OP who was using Outcomes in their assignments but did not show up in the Admin Analytics report. It appears that the instructor who *did* appear in the report did not attach outcomes to their rubrics, but assessed outside of the rubric structure. Further, other instructors present on the list in Admin Analytics showed having used Outcomes, but did not assess using them separately or in rubrics. They seemed to have been marked as using Outcomes in Admin Analytics just by adding them to their course, and I think the "use" may simply by associated with a user viewing the Outcomes page in their course. So, the data might not actually track the application of the Outcome to a rubric, but the instructor (as the Outcomes page is hidden from students) viewing the Outcomes page itself. Which is not super helpful for my purposes, because an instructor who has used Outcomes previously can import those same Outcomes into their new course with a rubric they intend to use again, or even from the rubric creation process, without ever visiting the Outcomes page of their course.
So...mystery solved? Maybe? Could be I'm just asking Admin Analytics to do something it wasn't designed/expected to do.