Residue left after mopping

Lately I've noticed my hardwood floor being a little sticky a while after being mopped. During the day when the sun hits inside you can see "tracks" from walking around with socks/shoes. I mopped with my steam mop and it got rid of it. I assumed it was maybe some dirty mop pads but I replaced them with clean ones and it's still leaving a residue/film. I actually change out pads and clean the machine/dock very frequently. If this isn't resolved, it will be useless to me. I'll just have to go back to steam mopping.

Maybe it's the cleaning solution you're using?