I've just upgraded from a TiVo Series 3 to a Roamio. When I access the program list on my old Series 3 through a web browser using the URL "https://<TivoIPAddr>/nowplaying/index.html" (after logging in with my MAK of course), it properly shows all the programs stored on it. When I try to access the program list on the Roamio in the same way, it only shows the 50 most recently recorded items. The bottom of the page says "50 items, (out of 62 total items)" with no way to access the missing items.
An item in this case mean either a program or a folder. If I switch to a folderless view using the link labeled "classic" at the bottom of the page to produce the URL "https://<TivoIPAddr>/nowplaying/index.html?Recurse=Yes", the behavior is the same: the browser only shows the most recent 50 programs, along with a message at the bottom declaring "50 items, (out of 193 total items)".
As suggested in other posts, I have tried adding qualifiers to the URL like "&ItemCount=200" to extend the item count or "&AnchorOffset=51&ItemCount=50" to move to the next page of items, but the Roamio simply ignores all of these qualifiers.