It seems that the latest batch of Bachmann 36-550 DCC decoders (Lenz LE1014Es in Bachmann packaging) have been reprogrammed by the chappies at Barwell in an attempt to get them to work better with their DCC command centre.
Unfortunately this reprogramming appears to fuff-up the running qualities when used with a standard Lenz command centres. Silent drive appears absent at low speeds, and any other number of problems seem to be present, including an unwillingness for locos to stop when running in one direction.
Fortunately it is relatively straight forward to rectify this by changing the R8 (Compact) or CV8 (with Sets 90 & 100) setting from 101 to 33. This simply resets factory default settings.