Pretty much just what it says in the title. Seems to be since the latest update to allow a component to auto resize to "hug content" (which was a nice addition btw), when a modal button that has been resized to be wider is disabled it shrinks to its default size. Haven't yet been able to find a work around.
This definitely looks like a bug. I have written up a report and submitted it to the engineering team. We'll make sure to follow up here once it is resolved!
As a workaround, you could hide the modal, then use a button with the following Event Handler:
