When creating or changing an Identity Safe password, various rules are listed by the software, including minimum 8 characters, one digit, etc. There is another rule which should definitely be listed: maximum password length is 20 characters!
When I changed to a new ~30 character password for the Safe, it was accepted as “strong” enough, but would not open the Safe. I was forced to delete the Safe and when choosing a password for the new one, it was rejected due to not including a digit. I could clearly see the 21st character was in fact a digit!
Having written some software, I deduced what was going on: only the first 20 characters were saved as a new password; then later the 30+ character password was compared to the 20-character stored version so of course they would never match.
If I had compared only the first 20 characters of my new password, it would have worked. Unfortunately the Norton tech assistant with whom I chatted did not know the max-rule either.
If the listed rules of the software had included the max limit, I would not have been required to rebuild 150+ logins from my back-up data.