X-H2S subject tracking miss

I've been experimenting with an X-H2 (not S) and have found the following: First, if you have AF-S set then there IS no tracking (I know you said you had AF-C, just trying to cover all bases). The camera just considers the whole screen as one "zone" and looks for the subject with most contrast. If you have AF-C on but no subject detection then it TRIES to keep a (non-adjustable-in-size) box on whatever it thinks your subject is, but fails most of the time. If you add subject, in your case, bird, detection then it tries the same thing as in my previous sentence but in addition, if it senses a bird, or a bird's eye, adds a small rectangular frame that's supposed to indicate the bird's eye.

In my tests with a single bird against a clear blue sky the subject tracking failed pretty often. To be fair, I don't have the "S" version so that should be better, but my feeling is people expect too much of a camera's subject tracking ability. Granted, the Sonys are probably at the top and don't fail very often but even they aren't anywhere near 100% (in my experience).

I don't do birds or fast moving object anymore, prefer the higher resolution of the plain X-H2, so it doesn't bother me, but if I was looking for the best subject high-speed tracking in the camera world I'd look at Sony (or maybe Canon), but even THEN people post what are to them disappointing experiences.