[MCM-1737] Custom Structures are not spawning in Sky Islands

Partner Rank: 1

Verification Builds: 1.20.51

Summary: Custom features are not working correctly when downloaded from the marketplace but work when imported manually to the game.

Impact: This affects the world that we published Sky Islands which was not working when players downloaded it, so we had to take it down. Players who purchased this world are unable to play the world as intended as the worlds selling point unplayable.

Also affects a multitude of maps currently in the QA pipeline.

Repro Steps:

Opening the world from the marketplace:

Open Sky Islands on the Marketplace (retail ID: aa3debc6-a2ea-45bc-b1e4-fda11d98ce94).
Observe that other then the spawn island no islands are generating and content log errors are appearing.

Opening the provided world (version 1.0.2.2).

Generate world from the template.
Observe that other islands are spawning around the spawn island.

Observed Results:

When download from the marketplace, our world (Sky Island) throws the following content log error's.

[Json][error]-Sky Islands | [Feature Registry Namespace Evaluation] Passed in contents could not be evaluated as valid JSON in the following file: /features/islands_select_island_filter.json 

[FeatureRegistry][error]-Sky Islands | No definition found for feature 'shapescape:islands_select_island_filter'

This causes the custom feature to not work, which will cause the custom Island generation to break.

The thing is, that when imported manually to the game (using the files that we submitted to auger) the features work fine and do not throw any content log errors.

We were not able find any errors in file mentioned in the content log.

We tried removing the molang in that file, to make sure that that was not the cause of the issue (version 1.3.0.0), but that prompted the following assertion error that content review send us back.

Assertion failed: Failed to unwrap feature!
Condition is false: false
Function: void __cdecl BiomeComponentLoading::_write<class BiomeDecorationAttributes<struct ConsolidatedFeatures>>(class CompoundTag &,const class BiomeDecorationAttributes<struct ConsolidatedFeatures> &,class IWorldRegistriesProvider &) in D:\a\_work\2\s\handheld\src\common\world\level\biome\components\BiomeDecorationAttributes.cpp @ 46

Expected Results:

Custom features should work the same way locally as when downloaded from the marketplace. Custom features should not throw errors for json files that use the correct syntax.

Screenshots/Videos attached:

Here is a video on how it looks when we test the world locally (using the same files we submit to Auger for version 1.3.0.0): https://www.youtube.com/watch?v=zwAizyyvufI

Regression Build:

1.20.51 (1.20.51.01_RC0, Win10, 20472182) and 1.20.51 retail when imported manually and not downloaded from the marketplace.