I have experienced this same issue but with .avi TV shows vs .iso movie files
Try to play a new file, gets about 5-10 seconds in and the video pauses but you can still hear the audio continue.
If you stop it and try to play any other file [including one you know worked before] results in a “Fatal Error” and hub reboots.
Even after the reboot if you try again same thing happens.
I have chalked it up to media library not auto scanning new material when turning it on.
I have resolved my issue by after xferring new data over, and turning it on i dont see the light on the front blink, I get up off my couch and walk over to the hub. Pull the power chord out of the back for 3-5 seconds and reinsert. This forces a compile and I can then play any of the files without a problem.
I have also been able to eliminate this up front as usually I xfer TV shows several ata time. So Ill xfer say 6 for example, when it gets to about 90% of the total xfer I turn the hub on, the hub recognizes new info being currently xferred and starts to compile and continues the compile till everything is finished.
If im not around or forget to catch it at the 90% mark. After its done I pull the power chord to force the compile. This way when I want to play the episode its already compiled and ready to go.
They need a button on the remote to force compile really easy and make their auto compile more efficient… just another bug.