I am having an issue with my shutter release when I have my speedlite on. My speedlite was flashing and working great for about 2 hours and then all of a sudden my shutter release on my camera stopped working. I did nothing different than when it was working before. My shutter release works just fine when the speedlite is turned off, but the moment I turn my speedlite back on, the shutter release stops working.
My speedlite is a Meke MK320.
I also tried my other speedlite which is a Neewer NW-670 and when that speedlite is powered on the shutter release and the flash does not flash.
I understand that the speedlite are not canon products but they are compatible with the Canon 6D, so I am wondering if you could possibly help with this issue.
I agree, it is not a Canon product. I disagree with the statement that it is compatible with Canon products. Your experiences seem to be proof that they are not compatible.
If you are having issues with the flash, then contact the manufacturer not Canon. When you read a User Guide for Canon Camera they refer you to the User Guide of the flash for instructions on how to use it.
If this is a new flash, then I highly recommend that you return it for a refund and purchase a Canon branded Speedlite.
One more thing. Does the camera recognize there is device on the hot shoe. You have to go into the menus and enable the hot shoe. No communication would not explain why your shutter will not fire.