If the new SIM works normally for calls and mobile data on the phone, the issue may be related to how Phone Link connects to the device rather than the SIM itself. I would first make sure Bluetooth is enabled on both devices, Phone Link and Link to Windows are updated, and the phone is properly paired with the same Microsoft account. It may also help to restart both the phone and PC and reconnect the device. If Phone Link still does not recognize the phone, checking the Link to Windows permissions and notification settings on the phone could help.