I'm on the 'Trainz Plus' stream, not the 'Trainz Plus Beta' stream - TRS19 build 103369, as I wrote earlier. Maybe that's why I can't find the 'Purchased' filter, you mentioned, anywhere.
On my (TRS19) CM, 'Beavermouth to Ottertail' shows up only under the 'All Content' filter as 'Not Installed, Payware (not active)' and I can't change that. Nothing (not even 'Sc525' shows up in-Game (i.e. after 'Start Trainz').
I've also tried 'Download Purchased Items' and looking in the 'Content Vault'.
Peter.