Password is wrong; but correct in the edit function

Potentially overstating the obvious but:
- Are you sure 1password is filling it (i.e. not your browser or something else)?
- If 1P is filling it, are there other entries with the same website url in your vault(s)?
Just to know exactly what you mean
- Is this on your iPhone/iPad or your Mac (and does the same happen on both?
And for clarification 
- "When I look at the password' -> as in click/tap and 'reveal password' it's wrong?
-  When you edit it it shows the right one?
- You are doing this on the 'same' device (i.e. either iOS or macOS) and show on one and fill on another (and/or they have synchronised)?

Sorry for asking that many questions, but the more insight the better the answer can be