Greetings scorpiofr33,
We have not received wide reports of users experiencing issues with the EOS Webcam Utility when using it with the EOS 90D camera. There are troubleshooting steps that you may take to see if the black screen issue can be resolved.
Please check and ensure that you are running with the latest version of the software which can be downloaded from the product support page for the camera:
https://www.usa.canon.com/support/p/eos-90d
Prior to connecting the camera to the computer, check to ensure that there is a memory card inserted into the camera and for the camera to be set in the movie recording mode. Disable the Wi-Fi function from the camera through its menu in case the wireless function is enabled.
Test a different USB cable and a different USB port on the computer. If using a USB hub, then we recommend on connecting the USB cable to a USB port directly on the computer or to disconnect any other device that may be connected to the hub.
When the camera is connected and powered on, please check to see if there may be any other type of software that is attempting to communicate with the camera since this may prevent the EOS Webcam Utility from communicating with the EOS 90D camera. Checking for other software that may be communicating with the camera includes any security software or security settings that may be preventing the EOS Webcam Utility software from detecting the camera.
If possible, test the camera and the EOS Webcam Utility software on a different computer. This may help to determine if there is something on the primary computer that is causing the black screen issue. We also recommend on testing different video conferencing software in case you're attempting to only use one. For example, check to see if OBS is able to provide a live image from the camera when the camera is connected. If so, then the issue is related to the specific software you are attempting to use. You may contact the developer for that software for further assistance.
