I think you're explaining another issue that's probably related?
My issue is specifically - the 2x image that is displayed on the storyboard/preview view much larger version that what I see when I run the app in simulator or physical device.
The only way to make the storyboard reflect what I see on device and simulator is by changing the simulated size of the view controller.
*This does not make the preview show the appropriate size. It also causes other issues and isn't a viable work around. It only makes the sizing appropriate in a superficial way.
I've tried to reply with a google doc that contains screenshots of what I'm seeing but it's stuck currently in moderation.
I've submitted a bug report for this issue (46118653)
This is a blocking issue for me currently.
Opening the project in xCode 9 Version 9.4.1 (9F2000) shows button images appropriately sized as expected.