Sync problem Macbook pro and new iPhone SE.

New-ish iPhone SE. Connecting to Macbook for Music Sync, no go after initial transfer from old SE phone.

Shows as location in Sidebar of Finder, Photos, Music

Photos can download new photos

Finder only option is Eject, or Restore to default settings (no sync/greyed out) Does show 256G capacity of phone, but not amount used. (briefly showed it could sync, then went away).

Music shows it in sidebar, but main screen shows iphone SE (2nd gen) 250.18Gb, but "Selected Device could not be found"

So I can't sync/backup using Finder, nor can I transfer music using Apple Music.

What can be done to clear this up so it syncs properly to Macbook?