it's not a bug (I think) any card that increases it's value if you are under the bust limit will keep the increased value and continue increasing if it is locked. it's just as it says on the card!
it's true that the 0.5 and pi cards increase their value on stand but the ace's effect is "while in play, value is 11 unless bust limit exceeded, then value changes to 1" so the value not resetting to 11 seems like a bug to me
