One World Will Not Load New Nether

When going into the portal, the game loads into the old nether. Not letting the player see/explore the new nether update.

 

Expected Result:

Player goes into the portal and is taken to the new nether update.

 

Actual Result:

Player goes into the portal and is taken to old nether.

How to reproduce:

I'm not very sure how to recreate this because this is affecting one world.I have provided a picture

This is a big bug because this has an affect on how the player can finish or complete the game with all materials.