Achievements become disabled in existing worlds with external behavior packs after updating to 26.50

Summary:
Achievements become disabled in an existing survival world when using an external behavior pack after updating to Minecraft Bedrock 26.50.

Steps to reproduce:

1. Open an existing survival world with achievements enabled.

2. Enable an external behavior pack/add-on.

3. Update Minecraft Bedrock Edition to version 26.50.

4. Open the same world.

5. Check the achievements status.

Expected result:
Achievements should remain enabled when using an external behavior pack/add-on, as they did before the 26.50 update.

Actual result:
Achievements become disabled after updating to version 26.50.

Additional information:

• The world is an existing survival world.

• Cheats were never enabled.

• The world was never switched to Creative mode.

• The same external behavior pack worked with achievements enabled around version 26.45.

• The issue appeared after updating to version 26.50.

• Other players have reported experiencing the same issue after the 26.50 update.

This appears to be a regression introduced in version 26.50. Please investigate whether the update is incorrectly detecting certain behavior packs/add-ons as incompatible with achievements.