Backup and Transfer iTunes Library iTunes - potential library.itl file issue

Monterey 12.5.1 and Music 1.2.5.7; 320gbs of music files

I have backed up my iTunes library regularly and have never had problems transferring the library between my laptops using the method, later supported by @turingtest2 as to "copy the entire ~/Music/Music folder from your old hard drive into ~/Music on the new one, then option-start-Music to select the (iTunes library.itl) library" into which I've copied it

What's odd / not working this time is that

1) the iTunes library.itl file isn't up to date (it lists a March date and it is now the end of August), and

2) the copied library doesn't read the songs added, playlist changes made etc since that March update

and therefore Music isn't reading the most up-to-date transferred library. All the songs (including March - August additions) have been transferred. It's simply that the library isn't reading them.

Any ideas, friends? Thanks!

n.b. that I've consolidated the library, organized it and copied the most recent "music library.musiclibrary" file into the copied library as well - none of which have solved the problem