I have never heard of this happening before, so I believe it is much more likely that some sort of error is involved with entering the password. Sometimes this is due to user error not remembering a capital letter or missing a punctuation character, or sometimes it can occur if you are using a different keyboard (physical or virtual), especially when international or other special characters are involved.
Unfortunately, if you don’t remember your password, there is no way to export your vault. Your only option is to copy and paste each item manually.