Hi. I have the same Problems. Shelly Blu Motion and The Bluetooth device is pending first connection to the cloud. The device is connectetd to Shelly Plus 1 PM. I tried everything really.
Reset
Reset with Shelly BLU Debug App
Firmware update with Shelly BLU Debug App
I tried a known good Shelly Plus 1 PM
Restart the Shelly Plus 1PM
Newest Firmware on Shelly Plus 1PM
i tried the old and new Android APP
i tried with I Phone app
Nothing. Always the same 
After a few Minutes the Blu Motion is completely disconnected in Shelly APP
Regards
Marco