I upgraded from model 2500x to model 4662x and the Dolby+ no longer passes through correctly and drops out. The 2500 still works correctly since it stopped updating at OS 9.1.0. The 4210 did work correctly until OS was Upgraded past 9.1.0 and it now fails. The 4662 on the latest upgrade has never worked. All 3 do work on a new TV of the same brand. It is obviously related to an OS update after 9.1.0 that disabled detection of the older LG TV audio. Data Follows. It should not be a difficult fix.