Custom structures are broken or with separated jigsaw pieces

The jigsaw pieces of a structure appears separated or broken

Steps to reproduce:

1. Import the .mcpack file next to the screenshot of this report

2. Create a flat world with this pack

3. Activate "Data-Driven Jigsaw Structures" experiment

4. In the world, put /place command

5. Choose the structure with mc

6. Put "IgnoreStartHeight" in true and "KeepJigsaws" in false

7. Look the structure

Expected results: 

The jigsaws of this structure must be completely connected

Obtained results:

The jigsaws are disconnected and generates some jigsaw pieces that are broken