What I am finding is if the previous PC->TiVo content was pulled with metadata they show-up as a folder and play fine.I did transfer some files from the Pc to the Tivo last night before the upgrade. Those play but its a little flaky, sometimes it sees them and others it says there is nothing there when I select it. They're both x264 mp4s I had pulled previously and edited the commercials out and compressed to an mp4 container to take with me while traveling. Have some others that were original untouched files and they play fine.
If the content was pulled to the TiVo w/o metadata there is no folder and they don't play. But if you delete them and recover them, you can play them once. also if you randomly scroll though the My Shows list they occasionally do show a folder and will be playable. The New UI appears to be folder/group dependent, even single recordings appear as a folder.