World templates from the Marketplace no longer function and instead generate as normal worlds

Steps to reproduce:

1. Create a new world with a world template

Observed result:
You do not enter the world that is supposed to be generated by the template, instead you enter a regular/superflat/void world.

Expected result:
You enter the world that is generated by the template.

Tested world templates:

• Halloween Mash-up Pack
• Neon District RTX
• Trial Chamber Legends
• 15 Year Journey
• Farm Life (by PixelHeads)
• Trident City (by Shaliquinn's Schematics)

Original description:
Some older worlds I have from the Marketplace no longer work when they are created or reopened. When I open these worlds that have already been created they change to appear like a normal world. My current known examples are the Farm Life world (made by PixelHeads) and the Trident City world (Shaliquinn's Schematics). Please fix this, as I have lost a world in which I have put in several hours building things. Below are the before and after images of the worlds. (also first report so i might have messed up)