Realms fails to load multiple resource packs from Marketplace Mash-Up template

Partner Team Reporting:

Spark Universe

Verification builds and Platforms:

1.20.0 - 1.21.1 win

Summary:

Mash-Ups with multiple resource packs are not all loaded on Realms when creating a world directly using Marketplace template.

Repro Steps:

1. Create a Realism Craft world from the Marketplace template directly on a Realm.
2. Observe that only the standard resource pack loads.
3. Note that the world-specific resource pack does not load for either the world creator or users joining the Realm. Causing custom blocks in the world to display purple/black or "?" textures.
4. For comparison, create a Realism Craft world in singleplayer using the Marketplace template.
5. Upload the singleplayer world to a Realm.
6. Observe that both the standard and world-specific resource packs load correctly in this scenario.

Observed Results:

When creating a Realism Craft world directly on a Realm from the Marketplace template, only the standard resource pack loads. The world-specific resource pack does not load for the world creator or users joining the Realm.

Expected Results:

Both the standard and world-specific resource packs should load correctly when creating a Realism Craft world directly on a Realm from the Marketplace template, similar to the behavior observed in singleplayer mode.

Impact:

Players are unable to fully experience Realism Craft on Realms as intended, affecting both creators and joiners. This issue does not occur in singleplayer mode, but breaks the use of Realism Craft on Realms.

Screenshots/Videos attached:

Yes

Notes:

• Product affected: Realism Craft 1.0, Realism Craft 1.1
• The issue is isolated to Realms and does not occur in singleplayer mode.
• When uploading a singleplayer world to a Realm, both resource packs load correctly.