The couple of times I've had ghost shifting on the RD, it was solved by increasing cable tension. This is particularly likely if cables have been recently replaced... after being in tension on the bike they can stretch a small amount compared to when they were brand new. Shimano manuals are usually detailed enough here but IIRC after setting high and low limit positions, you shift it to the smallest cog (actuate the shifter a few extra times to make sure the cable is fully released), then shift up the cassette to a middle gear (5th or 6th) and adjust cable tension such that the jockey wheels are dead nuts centered under the relevant sprocket. From there you may even need to back out the barrel adjuster (increase tension) slightly to keep it from ghosting in real riding conditions.
Quote:
Originally Posted by texbike
The chain rides up on the cog that it is on and causes clicking and popping as it stays in that gear.
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I'm interpreting this to mean you've got enough tension to shift the chain up to the next larger cog, but it's then not being held tensely enough to keep the chain dead centered on the cog, IOW the chain falls slightly back down the cassette.
Still guessing cable tension and/or possibly some slop in the shifter mechanism. I have not accumulated enough miles on a groupset to personally experience the latter.