Welcome, @BWolf.1, to the community!
We are sorry for any confusion this may cause, but IN6 (marked as INP6 in pinout view) is a single-ended input. It may be a little confusing that inputs like IN11 or IN14 are explicitly marked single-ended, which is just a left over from other derivatives in other packages of the same family where you can select differential and single-ended for the pin.
Summary: even if it is not explicitly marked single-ended on an ADC input - if it has no drop-down menu and can only be selected with a tick, then it is a single-ended input.
Does it answer your question?
Regards
/Peter