Keep in mind many devices using a USB-C connector are usually typically using the USB protocol which is not compatible with Thunderbolt 2. Check the symbol next to the USB-C port on the device to see which protocol the device is using with the USB-C port. If the device is using the Thunderbolt protocol, then it should have a lightning bolt icon....if the device is using the USB protocol, then it should have a symbol that looks like a trident. If the device has no symbol next to the USB-C port, then it is probably safe to assume it is using the USB protocol (Macs are the exception as Apple does not print any symbols next to the ports), but it is best to check the product documentation to confirm which protocol the device supports over the USB-C port.
Keep in mind "USB-C" is a connector desgination....not a protocol.