If you are 100% sure that your old wallet had a password, then either this recovered file is NOT the original wallet you were using... Or it was corrupted and unable to be properly recovered by your recovery software.
One last thought... Are you sure that Bitcoin Core is actually loading the recovered wallet file? It's possible that Bitcoin Core isn't even loading your recovered file but is using a newly generated wallet file...
How are you loading the recovered file into Bitcoin Core? Did you just rename it "wallet.dat" and put it in the Bitcoin Core datadir? Or does it have a different name?