The drop animation does not always load.

Steps:
1. Go to Landing Page creator in Studio.
2. Drop a block into a drop zone (as first block).
Result: Animation does not load. [NOK]
3. Drop a 2nd block into the same drop zone below the 1st block.
Result: Animation does not load. [NOK]
4. Drop a 3rd block into the same drop zone above the block at the top.
Result: Animation doest load. [OK]