Hi all,
I have the exact same problem, As I have installed the motion several times in the Shelly app to try to resolve it but with no luck.
So to clarify:
The motion sensor is installed in the Shelly app with no issue and the motion sensor also shows up in Alexa but when you trigger the motion sensor it does not show that it has been triggered in Alexa.
I re-installed the motion sensor again last night via the reset procedure as set down the instruction and then Alexa found it as a new device again as per other attempts but according to Alexa, the device has not triggered in 12hrs whereas the Shelly app shows all its triggerings up to the minute.
So any suggestion would be great.
regards
Darren