Nope. Tried 2 cables. The original cable and I also threw on a new cable from the shop just to cross it off the list that I tried it. No dice.
Keep in mind, the LX derailleur acts JUST FINE on both the old and new cable, while the Altus acts up with both cables.
It's not a cable issue. New drivetrain. Straight hanger. No obvious wear to derailleur. Decent tension, set properly, etc.
It's an issue directly isolated to the rear derailleur itself, nothing else. I'm just trying to understand from a mechanical standpoint what with the rear derailleur could have happened to cause those issues.