Changeling cannot exchange against a card with 3 or more costs gained by Dismantle (in the case of Smart Ask)
It may not be a Card Bugs as it's a configuration issue with Autoplay, but I'll post it here.
In game number 52651305, when I gain a card with 3 or more costs other than Skulk, I don't get the option to exchange that card for Changeling, I'm only asked if I want to exchange it for Gold.
Thanks for the report sangatsu, but this is intended.
"Smart Ask" knows you could have chosen a Changeling to gain with Dismantle, so it doesn't ask you. It's the same principle as not asking when you are buying a $3+ card with no related triggers; you could have chosen to buy Changeling instead.
That's why only Skulk and Experiment in that game cause Changeling to ask for an exchange, because they have triggers associated with their gain (and Skulk especially makes sense to exchange for a Changeling).