My Xiaomi Mi Band 3 was working well with Sleep as Android (paired with Mi Band Tools app), but just recently my phone updated to Android Pie (9) and Sleep as Android hasn’t been able to sense my watch ever since. Both the Mi Fit app and the Mi Band Tools app are still working fine and sensing the watch ok.
I’m suffering from what may be a similar problem, but I got a new Essential PH-1 and updated to Pie before installing everything and I’m using a Mi Band 2. I can’t get the Mi Band to connect with the Sleep As Android test or normal sleep.
I’ll second that. I’m on a Pixel XL with Pie and a Mi Band 3. I wasn’t sure initially because I got the band and the Pie update at around the same time.
If you haven’t already update to the 20180818 version, everything worked for me after I updated to that version.
My Mi Band 3 is working again after the latest Sleep as Android update! Now I can finally go to sleep.