Just updated to the new beta firmware (6.4.21), which says it "fixed support for sigma 18-35mm canon", but I'm having issues. With the sigma on, the camera freezes. Touch screen freezes, record button does not work, etc. Switch to another lens and everything works great. I can still view through the LCD in real time, even when the touch screen buttons are frozen.
Have installed a couple of times now, went back to older firmware and re-downloaded and installed 6.4.21 and same problem.
Any ideas here?