When transferring from the Avalanche® network to Ethereum, Metamask shows that 0 tokens are to be transferred, not the actual number of tokens. This is a known problem with Metamask.
For a more in-depth read on how the Avalanche Bridge™ works, please read the following articles.
For any additional questions, please visit our knowledge base or contact a support team member via the chat button at support.avax.network.