Turns out that I had to initialize the thumb drive since it would not mount. Never had this problem during earlier upgrades including earlier TNAP7 releases. Recordings are working fine now.Excellent! Thanks.
That narrows this down considerably. The next test should be:
1. Stay on Heroes ET SD.
2. Make a manual recording for 30–60 seconds.
3. Verify the .ts is created and plays.
4. Then create a brand-new one-time timer for Heroes ET SD, starting 1–2 minutes later and lasting 1 minute.
Verify these recordings work and are in the proper location.