Hi Tim,
I wish I had an answer for that but I don’t. I don’t know what’s causing the EKF to try to use Optical Flow. I hope Randy might have some insight on that. And I did a little searching and reading on the bad gyro health issue with Pixhawk2.1 and I find some reference to it, with some suggestions, but it doesn’t seem anything definitive. Anything from power it on, warm it up, then reboot. To maybe using the latest beta version of MP to “fix” it.
http://discuss.ardupilot.org/t/pixhawk-2-1-gyro-and-compass-problem/12936
In the past, bad gyro health meant a hardware problem and it rarely went away by changing software as it meant something was going south on the board. So unless one of the devs that is more familiar with the new code for the hardware can offer a suggestion, I’m at a bit of a loss to figure out what to do next. I’m sure you’ve loaded rc4 and not rc1, which I saw in one case “fixed” bad gyro health. Since you have it logging without being armed be interesting to see what the accel values are on the latest BIN file just sitting there on the bench not being moved. I only know mine (Pixhawk 1’s) show that it’s not being moved or vibrated in that situation. And they don’t change until it actually moves. And they both agree it’s not being moved. Your’s, that didn’t appear to be the case in the last flash log I looked at.