It seems like the problem is the settings.json file. It is automatically generated by Bitcoin Core and in testnet no wallets are produced but in mainnet I have all wallets.
Why don't you just share the debug.log? At least everyone here can figure out what the problem is, and If I may know where the settings.json (testnet) is located? Is it right in the X8/bitcoin/Bitcoin/testnet3/testnet3 folder or is it instead in the X8/bitcoin/Bitcoin/testnet3 folder?