I had to remove my two Samsung SmartCam HD Pro (SNH-P6410BN) from my hub. Afterwards when I try to add it back it does not detect it. The only troubleshooting step I could think of is to reset the cameras.
When you state remove, did that include removing/deleting it from ST (via the app or IDE)?
I had a similar issue a while back, and it can be a pita. If you’ve reset the camera, I found success by using the SmartCam phone app first, and then setting it up in ST.