I am not sure why you seem to get banded before interleaving I think is odd.
On my line I get banded when my sync is too low for the current band, so e.g. if I am on min 40 max 80 band and sync at 50, DLM will reband me to maybe 37 to 74 or min 40 max 60. Then if I sync at a higher speed and the banding is capping me it gets released a few days later, thats what I observed on my line.
Of course we know from you and kitz there is other triggers for banding as you seem to get it for error's, and kitz also got it for error's on her US.