I synced a few videos to the cloud. RasPlex will not play these. The error message indicates that I should check the file exists and the drive is mounted.
The web interface and PMP on my laptop - at the same location as the RasPlex Pi - play these videos just fine.
The data is stored on Google drive. RasPlex 1.6.~~3~~2. rPi 3.
If I can do something helpful to isolate the problem, please, let me know.