I bought the 85mm Art on January during a trip to Doha/Qatar.
The focus was totally inaccurate. After tons of shots with the 5D Mk IV in a tripod I could identify part of the nightmare - up to 1m showing front focus, after 2.5m show back focus.
Then, I bought the usb dock to try "calibrate" the focus. After everything updated I was ready to start
It just make grow a strong anger - totally inconsistent... in 3 or 4 shots at least in two the focus area was in different point.
I reset and start again countless times.
As I live in Brazil and bought during the trip, I can not return the copy. The Sigma assistance here is NOTHING.
It was my second Sigma lens, and was worse than the first experince.
I gave up
SIGMA NEVER, NEVER MORE !!!!!