Those are the final entries in the log. As before, the TV output switches off, the front display has just a green stripe on the bottom quarter and it needs a hard reboot to recover
Just in case it shows more (especially with CI) can you change to debug+ (Level 5) in log settings. … there are a few people with Ultimo4K under py3 without seeeing this issue, so I guess somewhere its your configuration (out of interest how is the usb attached… or is that an external HDD? Or?)