Trezor and Ledger may not recognize your FOX tokens, because they are not supported by the wallet. But do not worry! Your tokens are safely stored there. You can search the address your FOX tokens are stored on at etherscan.io to ensure they are stored at that address.
Only you - or the person who has access to your private keys - has access to any of your assets on your wallet. If you have more questions about the different types of wallets you can use with ShapeShift, check out this article: Walk Through of the ShapeShift Platform