I just tried both my problem movies again there now - The Martian Extended @ 26:20 and Black Hawk Down @ 14:36
Both problems still exist - sound drops out and audio out of sync after these points.
PLEX Server (on rack server Windows 10 PC): 1.26.0.5715
Client on NVidia Shield 2017: 8.21.2.27212
What is current situation? Am I using correct versions? Was bug fix rolled back or something?
ps. I did have my own report ticket about this problem which was entered before this massive ticket: PLEX audio dropouts and sync issues with seamless branching on 4K TrueHD/Atmos movies - #10 by geogan