Safari/Keychain Does Not Autofill Login Credentials After Migrating to new iMac...

i just migrated from 2015 to 2019 iMac (both with latest macOS Mojave), but when I logged in, opened Safari and tried to login to an account (ie Apple ID,..), Keychain could not autofill/find my login credentials. What happened? Keychain shows them but not from within Safari. I migrated my account, logged into Apple ID, and everything was set up the same as old iMac , yet almost all of my website ID/passwords were missing. I used a Time Machine ** (unchecked Applications only). I’m starting all over, erasing/reinstalling macOS.

Not sure what I can do differently. This is very frustrating. Losing confidence in Apple. 12 years and 4 iMacs later. Seems so easy and yet I always experience issues, even following instructions.