I'm a (annoyed) Canon shooter. I had a much older version of EOS webcam working fine. The real issue is Canon themselves - completely incompetent coding approach (presume outsourced, but maybe hand-off to new-hires/interns?). EOS webcam software has ALWAYS been poorly written, unstable, immature, and unreliable.
Unless you have a fairly new camera, you are working at USB2 speeds and therefore highly limited resolution. If your camera (model specific) has clean HDMI out, that is often the better approach that USB/EOS webcam util (and that is also true of any older DSLR with a USB2 interface)