It depends on what firmware you are running.
Android 9
- HW trasncoding broken when playing back on the Shield itself with PMS 1.25+. No fix yet.
- There maybe an issue with DD+ audio too with 1.24+ (still investigating)
Android 11
- HW transcoding broken regardless of PMS version. We are investigating some sort of incompatibility with Android 11. Not sure where the problem is.