No error given in console.
Webcam works as camera 
USB camera shows up under Sound and game controllers in Device manager
USB camera works with several other software apps OK.
POsted about this in 2017/2018
Has anything more been done to get the camera function working better with different camera devices as they appear in Device Manager?
What webcam make / model is it?
When you say “Webcam works as camera ” what do you mean, specifically?
The built in webcam on my lenova PC.
I plug in a USB capture device that allows analog rs-170 video to be captured via a video device.
Processing finds this camera in list but when used it fails to see a video input from it.
No errors, just blank screen
This same device works with several other 3rd party software fine, including Debut.
The only difference i can seeis that the device shows up in DEvice manager as a video device
and the webcam shows up as a webcam in DM.
I have another usb camera that shows up as a Imaging device in DM , and processing works with that ok .
I commented that I had the same problem with the external webcam, I bought a Genius Full HF 1080p webcam and after 2 hours of seeing forums I managed to connect it, what I did was first see the list of connected cameras and then connect based on the resolution , I leave the code, I hope it serves.
video=new Capture(this, 640, 480, "Genius Webcam");
opencv=new OpenCV(this, 640, 480);
noFill(); stroke(0,255,0); strokeWeight(3);