When attempting to take an item from a copper golem, the copper golem will not drop the item unless the player’s main hand is empty. In stable, this issue is worse; the player’s main hand, offhand, and armor slots must all be empty.
This is a significant difference in behavior from Java Edition, which does not care what the player is holding or wearing, and will always drop any held items.
This is working as intended per the changelog:
https://feedback.minecraft.net/hc/en-us/articles/39932063411213-Minecraft-Bedrock-Edition-1-21-111-The-Copper-Age