Over the past two weeks, I've noticed that despite using my 935 with my Garmin HRM Run (the detachable strap model) and getting all run dynamics, my anaerobic training effect on my workouts is abnormally low, less than 1.0 and often less than 0.5, even when I spend 25-50% or more of the workout in zone 5. I've double-checked my heart rate zones are correct in the watch and Garmin connect and the mobile app and the time in zone recorded does appear to match what I would expect.
The aerobic training effect appears to match what I'd expect based on previous workouts and perceived exertion.
I checked with a friend who has the 935 too and he noted the same, all workouts recently with an abnormally low anaerobic training effect.