Basically, it's sort of a bug, but you can work around it: There is sort of a 'hidden' parameter that controls whether the ribbon X resets or not. This is sometimes toggled on and off globally (not per-voice) in a strange fashion,
Quoting a post from a different site (this is the only post there you need)
"Not sure if anyone else has noticed this, but if you make a new patchand save it then assign a parameter to the X-axis of the ribbon itglitches. What I mean by this is, normally if you press the ribbon down and let go it will hold where you left off. If you switch to a factory patch where the ribbon X-axis is set to reset once letting go, then goback to your patch the X-axis now resets. The only way to get it towork properly again is to switch to another factory patch where theX-axis is set to hold, or turn the AN1x off and on again. Discoveredthis yesterday when I was trying to set up the X-axis to reset. Also if you switch from your patch with X-axis hold to another of your patcheswith X-axis reset and back to the first, the X-axis will still be set to hold on that first patch. If you still have all the original patches,or have replaced all of them you won't have this problem."
The chosen behaviour can maybe also be changed by sysex - I have not checked. Just passing on this info since I remembered reading it before. Also don't know whether it is ROM/OS version specific.