Hi, can you please check the following:
1. You can only set a faucet owner to be a user with the manage_wallets capability. Check that you have at least one user with that capability.
2. Once you do successfully set a user, you will not be able to claim funds from the faucet while logged in as that user. You will need to setup another account to test the faucet.
Also, are you on a multisite installation?
regards,
Alex