Probably bugged behavior. If I press a stance change that has hold down behavior while my character is busy, or if I go into a hold down stance, then a second one and do some moves from there, releasing the second stance will return to neutral instead of the first stance despite it being held the whole time. Releasing and repressing the first stance functions, but I often am accidentally in neutral stance when I mean to be somewhere else even though I press the buttons.
This should be solvable by checking anytime an action ends or a stance is released what buttons are being held. If this check already exists consider this a bug report.