For what it's worth, the solution I found - and which often works for me - was to move the views into a package.

Selecting the auto-generated scheme for the package and viewing the preview that way works a lot more reliably than with the app scheme.

This is quite a big commitment, since anything that the views rely on also have to move into a package, but luckily I tend to factor my code that way anyway, and I was in the process of moving my views across.