Wire.
Wow! I've only had mine for 2 years, I did spray lithium grease in a little cut out by the cable. Between the spool and the housing.
I'll have to check for the maintenance requirements.
Wire rope can sort of take a 'set' and be a 'bit' more hesitant to spool off....but I would wager just 'use' will free it up. You might check to be sure your winch clutch is fully disengaged. IF your winch will allow, put the lever/clutch in 'freespool' and just bump the 'in' button to see that it doesn't try to reel in.
But just pulling the line all the way out and re-spooling from time to time is usually enough to overcome any stickiness or new winch tolerance issues.