Yes, that did seem to be the issue - looks like all our season passes have set up to recordings+streaming videos by default. This has only seemed to have started to cause problems recently (i.e. last year or so) when I assume old seasons get re-added to the streaming database - but we now get regular (every 2 or 3 months) instances where suddenly the first 9 or 10 pages in "my shows" are all streaming seasons!
I have found a partial solution in that on the "my shows" options I can select "Recordings" as a filter and then that only displays the shows which contain recorded episodes (ie filters out all the ones that are streaming only) ... however, it still looks like it uses the date of the last streaming episode in the sort order and it seems to be that this may be linked to a database update date.
Nb as we've had VM TiVo since it was first available (had had the standalone TiVo before that since that came in so have been usign TiVo for about 25 years!) when I checked I discovered we've accumulated 750 season passes so its going to take sometime to sort them all out!