Biome Blending not happening in 1.18

Transition between Biomes from 1.17.41 to 1.18 leaving hard edges between chunks / Biomes.

Steps to recreate.
Update an Xbox one bedrock survival world from 1.17.41 to 1.18.
Render new chunks.
Observe harsh transition and lack of blending between old and new world's.

Expected outcome.
Old chunks will transition smoothly into new chunks.

Actual outcome.
Transition between old and new chunks is obvious and not blended properly.

Pictures attached.

This does not affect gameplay.