Issue reproduce steps:
1. Create a Minecraft Bedrock Addon
2. Create custom a entity.
3. Create custom a trade.
4. Add the custom entity's spawn egg to the custom trade.
5. Add the custom trade to a custom trader entity.
6. Create a minecraft world.
7. Add the addon to the minecraft world.
8. Join to the world.
9. Spawn to the trader entity.
10. Try to trade with the entity.

Expected result:
Entity offers a trade that includes custom spawn egg.

Observed result
Entity has empty trade page.