I haven't seen these specific issues mentioned but since my Roamio was updated to 20.4.1 (not on priority list), I have had lost connection issues with my mini (not yet updated).
The first morning after update, my mini claimed host box could not be found so could not access the now playing list but live tv worked perfectly. A restart of the Roamio fixed this. Since then, however, during live tv, the mini will lose its connection with a message that network troubles or host cannot be found. Reselecting live tv fixes this.
My mini is connected to Roamio through MoCa and has been rock solid since setup until now.
Also, I notice that no programs are listed on either box under "What to Watch Now" "Popular TV" while movies are listed in the other categories. Strange.