My music doesn't play, shows 'waiting' with a dotted cloud icon

This is what I'm seeing. I have some songs (elsewhere in the library) that are playable, but 99% of my library is like this.

I've tried dragging the previously downloaded Apple Music/Purchased songs from my HD into iTunes, and that only populates about a dozen records. If I enable 'sync' it'll now fill my library, including play count/rating but the cloud status stays like that. The library won't update, it'll do something and then freeze. Occasionally coming up with the 4010 & the other errors.

I've signed out of my iPhone/iPad too

I've tried going to apple music and adding a song to a playlist but then it said it needed to merge libraries, but now I can add songs to a playlist. It'll duplicate those records one, one 'apple music' and one 'waiting'. I can't add Apple Music songs to a library, it'll go through the motion of adding them, the icon cycles, but nothing comes of it.

2 - I

It's getting weird now.

I've added an album from Apple Music, it won't add that to my library but I can add it to a playlist, which then adds it to the library

It'll download all the records I don't have, but the ones I've previously downloaded show it as greyed out, with a dotted line

I'm usually quite tech savvy, but this has me stumped

I’ve tried that unfortunately. It imports about a dozen songs, but I have thousands.

once I’ve imported the songs from the external drive, I’ve turned on ‘sync’ and receive either a 4010 error, or an 18003 error (for genius)

does it make a difference if the downloaded songs are from Apple Music? I have a large chunk that I’ve purchased over the years, some CD imports, and the rest are Apple Music downloads

Even though it’s the same account, even saying the machine was already authorised, it won’t let me import them?

is there an easy way to repopulate my library? I have a lot of music, thousands of albums, going to each individually isn't feasible really.

it still says ‘waiting’ with the dotted logo

it's just frustrating that I can’t sign into a ‘new’ machine and use my library straight away

all my downloaded movies worked by dragging/dropping. I don’t get it

So I've just amended the table to show 'kind' - new records that I was able to download from Apple Music had 'Apple Music AAC Audio File', and then the half dozen or so that were imported had 'Purchased AAC Audio File'. The rest, as shown in the above image, don't have anything in that field.

I've opened an empty library, and that populated all the purchased records that just need downloading. 1462 purchased songs, maybe 12,000 records in total (from Apple Music) so 12%ish? I've just clicked on 'sync' for my Apple Music account, and it's reverted to the above image I posted. All the Purchased AAC stuff has disappeared

I'll give that a try.

Thanks for your help with this so far, it's appreciated!