I have to say that I'm quite often reading about that issue, also with other coins.
What I mean is that the same passphrase generates a different address (when entering it on different wallets, like web and desktop).
It may be on the users side, but I think devs should look into it. Maybe there's really a bug (with some specific passphrases only etc.)..
Every char you change gives another wallet address even if you add "space" at the beginning it will generate different wallet than one without space. We are using same algorithm across the board for ARK address generating so users should be careful to save whole passphrases and double check them.
This is what happened to me to but i did what a member had wrote for to do and worked fine when.After i cleared the cache from old wallet i reput the pass phrase in from the address i had saved and it came up as the correct address to match the pass phrase.Hope this helps you to if not just go back a couple pages and you will see the explaination