I have something that sounds similar - aside from volume, the only thing I use the knob for is to mark a track - should be 2 presses to mark, but sometimes it just doesn't take and I need to retry (occasionally many retries.) The same thing occasionally happens with a long down press to go to info screen - if I do it soon after a track has started playing (withing 7 or so seconds) it does nothing, but when I release it treats it as a short press and brings up the top level menu.
Tried various fixes, including setting the rate etc, but no change.
It doesn't bug me too much, but I wish I knew why it was glitching.
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Rory
MkIIa, blue lit buttons, memory upgrade, 1Tb in Subaru Forester STi
MkII, 240Gb in Mark Lord dock
MkII, 80Gb SSD in dock