in connectiq-sdk-win-3.1.7-2020-01-23-a3869d977 watchface diagnostics doesn't work

Actually, I found the root cause here as well as a work-around.

After you run an app in the sim the first time, the sim stays in high power mode, and when in high power mode, the stats aren't collected, so there's nothing to display.

Try this. 

Close the sim, and do a run that opens the sim and starts your watch face.  Then under settings, turn on low power mode.  If you view diagnostics, you'll see real data.

But if after that you do another run with the sim still open, no diagnostics, and toggling low power on/off doesn't help. The sim stays in high power, and onPartialUpdate is never called.

I'm using the 3.1.7 SDK, and to reproduce this, simply put a println in onPartialUpdate in a WF that does 1hz.  The first time you run it in the sim and drop to low power mode, you'll see the println.  Do another run without closing the sim, and in low power, no println calls are seen.

Actually, I found the root cause here as well as a work-around.

After you run an app in the sim the first time, the sim stays in high power mode, and when in high power mode, the stats aren't collected, so there's nothing to display.

Try this. 

Close the sim, and do a run that opens the sim and starts your watch face.  Then under settings, turn on low power mode.  If you view diagnostics, you'll see real data.

But if after that you do another run with the sim still open, no diagnostics, and toggling low power on/off doesn't help. The sim stays in high power, and onPartialUpdate is never called.

I'm using the 3.1.7 SDK, and to reproduce this, simply put a println in onPartialUpdate in a WF that does 1hz.  The first time you run it in the sim and drop to low power mode, you'll see the println.  Do another run without closing the sim, and in low power, no println calls are seen.