Extremely annoying, but not really urgent, and probably not something you can change, but ...
Opus (as well as 7-zip) cannot handle a password like '£%XXXXaaaa23,' (wh the quotes), whereas Winzip can.
Would be nice if you can convince 7-zip to change the behaviour, so it also works in Opus as it does in Winzip.
We get ZipX support from 7z.dll (more as a bonus, due to already usng it for several other formats), but we have no relationship with or influence over the 7z author.
However, he does listen to reports if you post then to his forum (he won't see them here). It'd be best if you posted it since you can then follow up with more details if he needs them, and there's no risk of the problem being misdescribed by us trying to redescribe what was described to us.
I believe ZipX, which WinZip invented, has issues with a lack of documentation and with 3rd parties implementing some of its algorithms, so it's quite possible the difference you're seeing is currently unknown to the 7z author