I know many have complained that the 1.5 firmware update really messed up the auto focus, I tracking, and for some people even freezing up their camera. If anybody has suffered any of this, please let Canon know by sending them a support ticket or calling them. We need them to fix this ASAP! Thanks.
I have had similar problems with an R5 with battery extender while using my 100-500mm ever since I upgraded to firmware 1.5. I am using AI Servo at the time with '*' Set to Eye focus and 'AF ON' set to focus. This problem happens consistently when I am watching a bird for a while and take my finger off the eye focus back button "*" on my camera. I consistently get a crash when the bird starts to move, I press the eye focus. The key is a pause of at least 5 minutes. One work around is the hit the AF On button (Set to focus) first. At one point I made the AF On button my eye focus button, same result. I have tried all the above suggestions with no luck at all. The issue does NOT happen when using any other lens. I had a friend out with me yesterday who had similar problems and then they stopped when he changed his crop factor on the red menu 1. Now no more issues. Try it, since you are probably shooting birds the crop helps. Canon Needs to fix the firmware.
