If the device is a motion sensor, then it’s not going to work if the hub thinks it’s a contact sensor.
Sometimes when a device is paired to the hub, the wrong kind of device handler gets assigned to the device.
Are you using the ST classic app or the newer ST (samsung connect) app?
You’ll probably need to login to the hub’s admin interface (also known as the integrated developer environment or IDE) with a desktop web browser to change the handler that was assigned to the device.
Since it sounds like that’s something you’ve never done before, start by reading this FAQ post on the use of custom code in ST. It doesn’t 100% apply to this situation, but it’s written in plain language and will introduce the web-based interface to you.
Alternatively, you could try to exclude and then re-pair your device to the hub. It’s possible that when it connects again, the hub will assign the correct handler.