The EDR returned a number of "false positives" for faulty assets. Beyond that, the repair did solve the problem.
For anyone who is unable to see content added within the last three to four weeks, follow these steps. Ideally, steps 1-8 should be performed when you do not plan to use your computer for up to eight hours at a time. This procedure is designed for TS12; some steps may be different for other versions of Trainz, including the Mac and iOS versions.
1) Exit Trainz completely.
2) Navigate to the UserData folder in the Trainz root directory.
3) Delete assets.tdx and the cache folder.
4) Launch Trainz and click Options in the Launcher.
5) You will have to enter your serial number(s) for all installed packs, including the base game, and your username and password.
6) Click OK.
7) Click Quit. An EDR will immediately initialize.
8) Wait. Depending on your computer's capabilities and the number of assets you have, the database repair could take several hours.
9) When the repair finishes, Trainz will exit. Monitor TADDaemon.exe in Task Manager until it self-terminates.
10) Launch Trainz again and click Content. A small database rebuild may commence. This should not take more than 30 minutes to complete.
11) Click the Faulty filter preset. Select all the assets, right-click, and choose "Show errors and warnings". Wait for the validation process to complete.
12) Close the popup and go down the list, single-clicking each asset to clear the faulty flag, until the interface refreshes and shows either an empty list or a shorter list containing only those assets that are truly faulty.
13) Go to File>Settings and re-enter all your personal settings for Content Manager.
Q: Where is my Trainz root directory?
A: By default, Trainz is installed to C:\Program Files\Auran or C:\Program Files\N3V Games. For 64-bit operating systems, these folders are found in C:\Program Files (x86).
Q: I can't delete the files.
A: You will need to be logged in as an administrator. You may also need to take full control of the directory where Trainz is installed. Click
here for a quick guide on how to do this.
Q: When changing the search filter, Content Manager seems to hang.
A: When this happens, close Content Manager. If it then stops responding, let Windows kill the process, and watch TADDaemon.exe in Task Manager. When that self-terminates, shut down your computer. Wait about a minute before powering it back up. After the computer settles on the Desktop, launch Trainz.
Q: The suggested steps did not solve the problem, or it introduced new problems.
A: I should have mentioned the disclaimer "Results may vary". This was tested and proven on only one copy of TS12.
Q: What if I have a different version of Trainz?
A: Consult an experienced user of your version of Trainz for the proper protocol.
Q: I forgot my serial numbers!
A: Go to your Planet Auran page and click "Serial Numbers". Copy and paste your serial number(s) from there.
Q: I forgot the username and/or password I used to install Trainz!
A: You're on your own for that one, I can't help you there.