Sigma doesn't support the use of the MC-11 with lenses other than their own recent Global Vision lenses. Even with those lenses Sigma doesn't support all native AF features. They don't support continuous AF. They don't support the highest burst rates.
Thanks for the comment on my images. Just to let you know, they were taken with my original EF 100 Macro, not the EF 100 Macro L you are interested in. Some of my equipment is for professional work, not for the images I post on my website or on these forums. So I just mounted my EF 100 Macro L on my A7R IV for the first time to make sure it works. CAF worked, though a little slow and it was very noisy with the USM, but, just like on my other Canon and Sigma EF mount lenses, works. The following distance was from 16 feet right up to MFD and all images were in focus. Sigma's website does say that it does not support CAF on the lenses I use. It is the only feature they are currently cautioning about for them. Yet I use my Canon and Sigma EF mount lenses interchangeably with my native Sony mount lenses on the A7R IV, my only Sony still image camera. Note that this would not have been the case if I didn't update the MC-11 to the latest firmware. Before that update, none of the lenses worked very well. Afterwards, I've had no real problems. I can now even do birds in flight.
