Characteristics

@journeyman4
It's not clear what you mean with "...one of those zeroes with a line through it...", or at least what your issue with these is.

In common computer fonts, there are o, O and 0, 0. The former two are small and big letter O (ohh), the latter two are the same digit 0 (zero) displayed in two different fonts, one without and one with a line through it. There exist also the less common characters "Ø" and "ø". These are from northern european languages and are pronounced similar to the German "Ö" (O Umlaut). They look like a slashed zero, but are characters.
You need to look very thoroughly which of the characters is actually displayed. O and 0 are not the same. Similar thing is l and I (small L and big i) by the way.

You need to make sure you enter exactly the same letter or digit you entered previously. Different letters might look similar to each other, but they are different for the computer and for a password. If this is actually your issue, I recommend you make yourself familiar with the basics of computer usage, since this is actually no issue with 1Password but with the general understanding of how the text processing of computers work. And that the same text might look different if displayed with a different font - it's still the same text.