We had this exact same problem on a brand new Brandt (new as of Jan 2016)
Was mind-numbing frustrating. Almost shut us down several times just because we couldn't band paint grade. Happened on 0.5 and 1.0mm wood.
Almost never happened on PVC.
Had all 4 of my best machine-minded guys in the shop get utterly stumped at it.
Sent Service Tech #1. He was totally baffled. Suspected the press roller was not square to the beam. Measured it, found it to be fine by his eyes. Gave us a temporary workaround that amounted to having the band held almost excessively tight before it hit the glue spreader and press roller.
Service Tech #2 came. He pulled the machine apart more than Tech #1 did, at the press roller. Measured for square in a different way, and found the press roller was 3mm out (!!!!!).
He corrected it, problem solved.
Since then, we've had maybe one every few months happened that we chalked up to odd band grain, but if it gets more frequent, we'd check for square again.
I would absolutely pull that machine apart (as needed) and check your press roller for square. You know your machine better than I do, so you will have to decide the right way to measure it.