There was an error while attempting to retrieve data from the selected DVR

I'm using TivoDesktop and have used it successfully for a number of years. I've been using it just fine with my Roamio Pro since 2013. This weekend, I started getting the error message "There was an error while attempting to retrieve data from the selected DVR. The system cannot find the file specified." TivoDesktop can see the Roamio Plus, and the error comes after it counts down through the 749 recordings. The Roamio Plus can see and access the recordings on my computer through TivoDesktop. I have TivoDesktop running on other computers, with the same result. I have a premiere and an elite also, and TivoDesktop continues to be able to access those. I've had 20.4.6 on the Roamio for a couple of weeks, so no immediate impact from that. I've reinstalled Tivo Desktop, rebooted everything, changed the Roamio's name, and deauthorized and reauthorized on the website. I can access the shows by using https and the TiVo ip address. Any help would be greatly appreciated. thanks