I'm on thin ice here since I sold my Beatstep a while ago, and I might be confusing this with the Novation Nocturn, but I believe that turning a knob slowly results in the values 65 or 63 being sent, depending on direction, but turning the knob faster results in larger offsets from 64, e.g. 66 or 67 when turning fast to the right.
If this in fact is the case, then the patch should not just compare against 65, but rather subtract the value 64 from the CC value to get a value to be added or subtracted. It would require changes to the RotEncSelector object in order to accept not just steps of 1 but arbitrarily large steps.
Don't take my word for it though, try it with a MIDI monitor or Axoloti patch to display CC values.
(Side note: The Nocturn does register itself as a MIDI device although it does output MIDI data. There has been a patch in the Linux USB quirks table to recognize it for a while now though; I don't know what there is for other platforms, I think the standard Novation driver can't be coaxed into generating standard MIDI data).