Hisense Plex no longer playing files that have been played before (multiple formats)


Up until recently, the Plex app on my TV was playing everything perfectly. All formats played... .AVI, .mp4, .mkv - But up until a few days ago, some files would no longer load, while others would. Playback is not an issue on the iPad app, or the server. Just the TV.

For instance, I wanted to watch "Before we go" (the file type is .mp4). Works elsewhere, just not on the TV. Same goes for an episode of "Younger" (.mkv), an ep of "the Originals" (.mkv - while another .mkv file/ep of the same show does play). My toddler wanted "Jurassic World", watched it 100x before through TV app, but now won't play (.AVI). He's currently watching "Minions" which is an .AVI file and it's playing perfectly.

Did a factory reset on TV, didn't change.

Am at a loss. Not sure what else can be done.
Would really appreciate some help please...