the effect of having your outfeed table too low (~0.005") relative to the knives (i.e. knives too high) causes a taper meaning that w/ repeated passes, you never hear the last few inches (or more) of the board being planed. So of course you continue to pass the board over the jointer trying to get a flat face, yet never seem to joint the last foot or few inches. And yes, this board is not flat. It's kind of the opposite of snipe. The terminology is typically referred to as cutting a taper, b/c when viewed in relation to the other face, whether they were precisely parallel or not to start, repeated passes will cause a very obvious taper on the jointed face as you remove material from one end but less and less from the other end as you pass the board over the jointer. But again, that face is not flat so yes, the jointer would not be setup correctly in this instance. Raise the outfeed table a hair or two and try again. Mine has shifted on me before, perhaps a temp change or someone banged it w/o mentioning it to me. It's not an uncommon problem and is easily remedied by raising the table. Ruler trick, dial indicator, etc. many ways to check it.
HTH,
Sam