Rant: check the derailleur hanger alignment before you touch the cable tension
Spent two hours chasing a ghost on a customer's 11 speed that would not shift into the top three cogs no matter how much barrel adjuster I fed it, then finally threw the DAG-2 on the hanger and it was bent 4mm in. Straightened it in five minutes and it indexed perfect on the first try. Anybody else get burned skipping that step because the customer swears they never dropped the bike?