Content item preview disappears after turning overflow on.

Steps:
1. Create a new Landing Page (min. 2 zones).
2. Add a Schedule block to each zone. Optional: rename 2nd block and change template to list.
3. Add a content item to 1st block (e.g. blog post). [screenshot 1]
4. Turn overflow from 1st block to 2nd on.
Issue: Preview disappears from 1st block. [screenshot 3]

Optional steps:
5. Add a content item to 2nd block.
6. Publish (confirm if empty slots).

Remarks: After publishing both blocks look alright in view mode. Also when returning to edit mode both blocks have preview generated.