This happens with grouped buttons which are simply on the layout, no need to click in my case, its broken from the word start.
The text area expands causing the button background to expand with it.
I thought perhaps setting the font to 'no-color' would be new way of doing this without the work around of 500px, but it just turns text white.
One idea I just came up with is:
As the button label use : <<$$var>>
Then in the conditional formatting calculations use something like:
Case ( Table::Field = "value" ; Let ($$var = "Click Me" ; 1) ; Let ($$var = "" ; 1))
I tried it with local variables and it appeared to work ok too, changing without a refresh of the screen, of course I have not tried it extensively, it was a quick thought...