Is it battery or USB powered?
If battery, then maybe the routing is not right, try wake up the sensor after you install it in the final location (press the button once) as well as “heal” in the z-wave developers tool.
If USB powered, then also wake up after final location.
If no joy, unplug Homey for 10-15 minutes.
Last resort, exclude and include again the sensor. Keep it this time close to Homey after inclusion and see if motion reports in a while.
Mines are USB powered and all three had similar problem. After inclusion, I kept them first close to Homey until the motion was reported (before it was dash -) and then locate them to their place and pushed the button again. That worked for me.
Hope this helps.