I have a computer dedicated to Video Ai at my work. I set it to upscale to 4k and and the render time is 16 hours. So I start it in the morning when I get to work at 5am and so it SHOULD be finished when I get to work the next day. However when I come in the client is closed, the output file that was building in size the day prior (around 15gb when I left work) is now back to 0 and when I open the client the upscale starts all over again with no error notifications. This has happened 3 days in a row now. I just upgraded to the most recent version and still did it.
Open the Preferences Panel and make sure that the AI Processor is set to your RTX 4070 and that lower the max memory to 90% and save those settings. Also make sure that the computer is not going to sleep or running any overnight updates from Windows or anything.