Overflow target schedule block changes depend on the position of the slider on the timeline in the source schedule block.

Steps:
1. Create a new LP with at least 2 zones.
2. Add two schedule blocks, one per zone.
3. Set overflow (from hero to grid).
4. Add 4 content items to 1st block (hero) with ca. 2 hour gaps. Confirm overflow for items 2-4.
5. Check the timeline for 1st block. (move the timeline slider after the last change)
[4 changes are visible]
6. Check the timeline for 2nd block.
Result: 3 changes are visible. (and are shifted to the left by one EZS-752)
7. Select 1st block, move the slider after the 3rd change.
8. Check the timeline for 2nd block.
Result: 2 changes are visible.
9. Select 1st block, move the slider after the 2nd change.
10. Check the timeline for 2nd block.
Result: 1 change is visible.
11. Select 1st block, move the slider after the 1st change.
12. Check the timeline for 2nd block.
Result: no changes are visible.