After migrating a site via Snapshot & upgrading DB, I cannot login

Hello - I migrated a site from a multisite to a stand alone WordPress install. The migration worked perfectly except that I now cannot log into the site. When I went to the wp-admin screen right after I restored the snapshot file, it said I needed to upgrade my database so I did. Then, I tried to login with both the username and password from the old site and the username and pw from the stand alone site and neither work. I also tried to recover the lost password using these usernames and they are not showing up as registered usernames. I tried clearing cookies and cache and searched extensively with no luck. Any thoughts on what is causing this? Is this a database issue?

Thanks,
Brandon Johnson