I don't have the device so not very useful from me but what driver are you using? Generic Zigbee outlet? I think it's the wrong driver you are using that's why it's not showing up.
I have a couple of them, correct driver is the "generic zibgee outet". Yes, they are sluggish when you try to add them, it can take up to a couple of minutes. They will add as a "device" (if I remember correctly) for the driver initially, you have to change it to the correct driver and then press configure and refresh.
Agree with @halfrican.ak. I have one and it took forever to pair but once it pairs it works fine and reports power too. I don't know what it is about ST branded sensors and Hubitat but my ST branded water sensors took forever to pair as well.
One thing to keep in mind is that ST sensors are picky on the zigbee channel. 26 for example doesn't work. You can find a few threads on this topic.
I didn't really like the way these worked in Hubitat because the Generic Zigbee outlet driver never knew the state of the outlet (On/Off). Always showed off even when on. This made it difficult to use with the dashboard because the state would be indicated inaccurately. I replaced my last one today with a zooz ZEN15 Zwave plus switch. State is being reported correctly now, and one less zigbee device. I prefer Zwave plus. The Zooz seems to be heavy duty, and reports energy usage.
Is there a way to see that without deleting the device and adding it back? Iād hate to have to go through this again. But I will if that is the only option.