I just had a lightbulb moment! I'm not sure if anyone is familiar with the Tokina 50-135mm f2.8G, nut the manula focusing sleeve is able to slip forward and back to pop itself in and out of manual to auto focus as opposed to doing on camera. A few times not after I've had it in manual, when I slide the cuff back to auto the camera isn't engaging with the lens' autofocus screw and spinning. I have to play with the cuff a few times till the autofocus screw grabs. Now I wonder if the lens is at fault. I'm going to run the camera with a few other lens.