AVAX aren’t on BSC chain. They are still on Avalanche C Chain.
Actually, to make it simple C chain / BSC / Ethereum are using the same address format => all can be linked to Metamask but with different RPC.
A same address can thus be used for the 3 blockchains. Just need different custom RPC.
In this case you sent your funds to a ETH like format address from C chain to C chain but only used by his creator ( Binance ) for BSC.
Tokens doesn’t appear because on each chain AVAX tokens contract are different and not readable by the other blockchain.
=> They only have to use the private key / seeds of this address and connect to Avalanche C chain RPC or Avalanche wallet and the funds will be there. Then, simply execute a trx to your Metamask address and it is solved …
We can clearly and easily see your AVAX and WBTC on C chain