I’ve created a single layout for a custom posttype. That custom posttype used a lot of ACF-fields for its content. Thanks to the amazing flexibility of Loopers, I’ve been able to create a very flexible way of generating content that’s easy to manage and shares a consistent layout. Hooray for Pro on this 
The catch: WPML is not translating any single part of this Single Layout. Not the ACF-fields, but also not the text-elements of the single layout. Nothing.
After years of struggle with Pro / WPML, it looked like things got better after migrating from shortcode-storage to HTML-storage, but as it turns out I’m running into issues now I’ve started using a Pro Single Layout.
I’ve also created an archive-layout for this CPT, which shows similar issues.
I’ve shared the real world example in a private note, but I’d be happy to share the solution as a public post, hoping this might help others in the future.