Give the Scan some time by launching the scan and then running a clock timer.
We have found that to use other devices like microcontrollers it is (more often than not) necessary to switch on Location, a Google Security requirement. To trigger that, simply drag a location sensor component into the Project. That may affect the scan, I really don't know.
The latest BLE extension is version 20201223, package name 'BLE-device-sort.aix'
If your App is going to be installed on a Smartwatch, keep it as lean as possible else it could exceed the memory allocation.
Also, make sure the Smartwatch is actually using BLE, that's not a given, many wearable devices still use BT Classic.
https://www.professorcad.co.uk/appinventortips#TipsBluetooth
