Canon EF 16-35mm f/4 low light focus

[LovePhotography]

Anyone else surprised that their 16-35 f/4 (on an EOS 6D) doesn't perform better at low light auto focus (that my iPhone 7 handled without difficulty)? More importantly, would a new 16-35mm f/2.8 done better on auto-focus?
(Subject was a party of about 20 around a fire pit with several tiki oil torches in the area- cropped to get it below 5 MB).
Thanks.

 

[Eldar]

What AF setup/mode and which focus points were you using?

 

[Kuja]

With some of my Canon cameras, the AF system always gets confused if I have a source of bright light in a dark scene.
Maybe the fire and the torches torches have caused this?

 

[BillB]

What shutter speed was used?

 

[geekpower]

the only negative behavior i would expect in low light would be hunting, in which case you can always use the AF assist from a flash (with the flash itself set not to fire, if you don't want it)

the pic here confuses me. i would try one-shot mode, which shouldn't let you take a shot until it gets focus.