Another and likely possibility is that the upper jockey pulley bearings/bushing may be worn enough to give the pulley too much sideways (lateral) movement, which would allow the chain to move the pulley far enough to the side and allow the derailleur cage to interfere with the chain. That pulley has a small amount of sideplay built in, about 1mm in either direction. If that's the case, it's time for a new pulley.