Ah, this is the part I was missing.
Are your buttons invisible by default (“Collapsed” is probably most appropriate)? Because you’re not explicitly hiding the other button in the 4th image, so if they’re not invisible by default that might be the issue. If so, either set them both to be invisible by default, or add SetVisibility nodes to the 4th image to set the “other” button invisible (Resume Visible => Reload Collapsed; Reload Visible => Resume Collapsed).