I believe I may have a similar issue, but mine has gone from annoying to scary
I also recently had the 24k valve inspection done by BMW, but this issue was present BEFORE the servicing
... Although, is does seem a little WORSE since the servicing
For quite some time my bike has made an intermittent 'rattling' noise while idling... Sometimes it would be only during warm-up, but other times even after bike had been running high RPM on freeway then stopping at a light, making noise at idle. Bike runs just fine at higher RPMs, issue is only noticeable around 1-1.5k RPM...
Also, while engine is 'rattling', idle RPM is erratic. It will fluctuate between 900-1.3k RPM erratically as if it is fighting to keep stable operation.
After reading above, I tightened all bolts mounting the headers to the case
... They did tighten up a bit, but issue still exists.
I have uploaded a sound clip to YouTube of the symptom, pay close attention to engine after I rev it up to 2k RPM, when it falls back to idle it goes to shit. Gets terrible around the middle-end of the clip....
(Sound captured from clutch-side of engine, approx. 10in away from case.)
Please help. My baby sounds like she's dying