My loose ball BB keeps coming loose (or misadjusted) after riding a few miles.
When I first install it, I make sure it is properly adjusted (no play, I check with the crankarm attached). Then I crank down really hard on the lockring, making sure to hold the adjustable cup in its proper position. Again, I check to make sure there is no play.
But after a short ride, there will be noticeable play in the cranks. The lockring doesn't feel loose. It just feels like it is misadjusted.