When I look at your pbParams the U2 Band plan medley phase show only a certain amount of tones is available to you and U0 & U1 shows all tones being available for each Band
Discovery Phase (Initial) Band Plan
US: (6,31) (882,1193) (1984,2770)
DS: (33,857) (1218,1959) (2795,4083)
Medley Phase (Final) Band Plan
US: (6,31) (882,1193) (1984,2093)
DS: (41,857) (1218,1959) (2795,4083)
Yes it looks like crosstalk has knocked out 677 tones but I don't think this is down to a rouge crosstalkers modem all you have done is to increase the Bits available on this U1 band via the UPBO switch more Bits or bins = higher sync and I know what crosstalk looks and feels like it's going to annoy other CPE with DSLAM resyncs occurring.