Even using a space could create problems.
He is saying that coins are still there and nothing moved, so he is obviously making some mistake with passphrase.
Spaces can cause issues, I checked that with
https://iancoleman.io/bip39/ script. Leading or trailing spaces or multiple consecutive spaces in optional additional mnemonic passphrase all yield distinct wallets and keys.
Electrum behaves the same with BIP39 mnemonic seed words and with "dangerous" spaces spits out a warning:
Warning: You have multiple consecutive whitespaces or leading/trailing whitespaces in your passphrase. This is discouraged. Due to a bug, old versions of Electrum will NOT be creating the same wallet as newer versions or other software.
BUT Electrum with Electrum mnemonic seed behaves differently: the optional additional mnemonic passphrase is sanitized and leading or trailing spaces are removed, multiple consecutive spaces between other characters are replaced by a single space.
I guess that's documented somewhere...
I didn't know that Electrum wallet is displaying error message like that, but this could be better than opening wallet with zero balance
It must display an error message because the hardware wallet device can't properly provide the correct secret to unencrypt the wallet. Being quiet and opening the wrong wallet would clearly be the wrong action in such a setup.
6. Write down and backup your passphrase, not just your seed words.
And better not store it together with the mnemonic seed words as then the optional mnemonic passphrase makes not much sense (to me), you gain no additional security for your wallet if stored together.