Hi there,
So I’ve compiled and run your sketch and with the Power Profiler II and the Nrf_connect for desktop BLE, I see when powered on it’s advertising and connectable AOK. However The PPKII shows the sleep is no-where near the posted numbers. I still see 20ma. during sleep? (see pics)
after a minute(60-sec) , BLE Scan shows it goes offline. not connectable.
So I’m betting the Battery is Dead or below a functional level.
here is the Wake_Up which takes more than a double tap BTW,
It does register a step and the BLE notify works sending the data.
the PPK shows it’s never reaching deep sleep.
I’m using a CR2450 coin cell FYI.
I think maybe when you sleep , you need to change the IMU from STEP cadence to ONLY Double-Tap awakable? if that make sense. perhaps it will be lower, YMMV
HTH
GL
PJ 
PS. Battery Monitor Service Appears to work well.
I went back and loaded BSP 1.1.5 and same but slightly lower Power with that, still not great!
It’s running for a day , see if it’s alive tonight?