Is it possible someone hacked my bitcoins?

Hi, I have trouble recovering my bitcoin wallet using the mnemonic. I get "invalid mnemonic" phrase. Funny thing is that my seed words are written on 5 different pieces of paper and mnemonic password is exactly the same on all copies. So I find it very unlikely that it is incorrect. I also have another wallet, which I did not have any trouble recovering using the mnemonic. Is it possible someone hacked my wallet, so that I cannot access it, or am I being completely stupid?