The Sony A7C is not supported in Lightroom yet. Our engineers are working with our partners to get the camera supported in our future updates.
Please note that if your camera came out within the past 90 days and it’s not on thelist of supported cameras, be patient, as you may need to wait for compatibility.
Adobe goes through a rigorous process of adding support for and testing of each new camera raw format. Adobe generally releases updates of the Adobe Camera Raw plug-in and Lightroom to provide new camera support about once a quarter, or about every 90 days.