I have a SIGMA 50-500 that I loaned to a good friend. When it came back it would not auto-focus. Friend said it got "bumped". I think they meant it got dropped.
My Sigma 70-300 stopped working after updating firmware on my Nikon 7100, to latest firmware. 103 to 104.
Reverted to previous firmware, all ok.
Would not have though that would be the cause, but thanks to the internet, it is a fact.
Probably Sigma would update the lens firmware, if you send it to Sigma, but there sees to be nothing in the 7100's latest firmware that affects me.
We will see if there are any more updates to the 7100's, that Nikon addresses this issue.
If you want to reply, then
register here. Registration is free and your account is created instantly, so you can post right away.