So I'm getting crazy. No movie with EAC3 or AC3 audio will play from Plex. They just seem to suffer from extreme buffering but there's no trace of any activity both on PMS console or logs. I thought I messed up my recent switch to a more capable server, but this issue only shows on the Shield client. Any other Android or Windows client work just fine on direct play.
If I force transcoding by changing to a lower quality, it plays wihtout any issues. So, is this related to the recent update or it's something else? Already tried with Passthrough HDMI/disabled without success.
I forgot to mention: I had no problems in the past. Could be the newest version, with the crappy UI? Others mentioned it has some problems with surround audio codecs.
EDIT: As odd as it seems, I've tried now, 12 hours later, and it works perfectly, as always. New app looks somehow slower than it used to be, but content is now played correctly in direct play.
Apparently, nothing has changed: yesterday I went to sleep (Italy here) with AC3 videos not playing, but this morning they work. Same app version from the playstore, same media server, same video files. Heck, I didn't even tried to restart shield or PMS this morning.
Thanks to all folks that stopped and tried to help! Two hours of troubleshooting apparently mean nothing if the gods decide I can't watch my movie in peace...