Does Built-in Payware not Active just indicate that no loaded route uses that asset?
No. That means anything route, even one's you worked on yourself and included payware will be missing assets.
If you want to fix this you can try:
1) Removing and reentering your username in the settings.
This may force a reconnect to the server.
or...
2) Open up the Packages folder located in your T:ANE data folder. (The same applies to TRS19).
Ex. E:\TANE_DATA\Packages - the location of my own T:ANE data and packages folder.
Delete all the SC folders.
When done, defrag the hard drive (Close Launcher first).
Start up again and at the Launcher, run a database repair.
When completed, download purchased items - click on File menu Download purchased items, to force a download when starting up Trainz again.