After looking at this bottle sitting on my basement floor for years, I finally got around to opening it and checking what is smelled like. My buddy filmed the opening
smelling old yeast
Upshot is, it smelled yeasty, with some sherry notes due to oxidation. Nothing I would consider an off aroma at all. This had been sitting in my basement for at least 2, if not 3 years (50 F in winter, 70 F in summer). In hindsight, perhaps I should have tasted it as well.........
This really tells me that any strong off aromas that people think are due to yeast autolysis, are not due to yeast autolysis, but something else. The most likely culprit being an infection.
Autolysis is a normal part of the yeast life cycle and begins as soon as the bulk of fermentation is done. It can affect the flavor of the beer when left on the yeast for a long time BUT THIS IS NOT A BAD THING! It does not result in strong off flavors, in fact many folks like the flavors it adds! If it smells and /or tastes bad, don't blame the yeast - they're innocent. Look elsewhere for the cause