This issue has been around for so long, you used to be able to uninstall the app and reinstall (which is a pain as you have redownload all your offline playlists which takes hours) and the device would reappear in the desktop client and start downloading. Now you'e removed the device appearing in the desktop client meaning you have no clue if it's actually doing anything (of which it appears it isn't).

You need to start from sratch and rebuild this process as googling it shows so many users having similar/same issues.

I have the client installed on my PC, local files are there and I can play them from the desktop client. I add them to a playlist on my desktop client and they continue to play. I then go to my mobile device with a fresh install, login, select the playlist with local files from my laptop on and files from the actual Spotify library and choose "availble offline". It proceeds to download the Spotify library but not the local files.

There is no way of telling if the mobile device has found the desktop device as there is nothing to show it's seen either side in the app. You can't enter the name/ip of the desktop client to try and force it. You can't connect your phone via the USB lead to get it to do it either.

I've been a premium subscriber since the begining, but this is just getting more and more difficult and worse and worse as time progresses. Stop doing new things if you can't get the existing stuff working.

This whole thing makes Apple music look more and more tempting.