Issue:

Upon applying the built-in "Mario Mash-Up" resource pack to a world, the pack does not load, rendering it useless. Attempting to reload / reinstall Minecraft or the Mash-up does nothing. The pack cannot be reinstalled via marketplace as it hasn't been published.

Expected Result:

Mash-Up loads like normal, altering the games looks

Result:

Pack does not load, using the same assets from the unmodified game.

Conclusion:

If there is a way to fix this, please let me know. As I have no idea to fix this. If this is a problem with the recent updates to the game, please let me know.

Thank you.