I can only attribute your experience to the use of HD Homerun as your outboard OTA tuner, which I myself have no experience with.
I don't need any addon/plugin to see thumbnails of my recorded programs. I have a pure WMC setup with internal (a) ATI TV Wonder 650 PCI 1-tuner card, for OTA/ATSC, and (b) Ceton 4-tuner cablecard-enabled tuner card, for TWC/LA cable programming.
And my WMC setup (with no 3rd-party plugins, aside from MyChannelLogos which adds logos to the Guide as well as increasing the number of rows shown in the Guide to 10) does exactly what I want (I have my recordings sorted by <TITLE> and then "view list" (rather than "view large").
This give me an alphabetical "folder view" by program name, with a major "folder" for each recorded program that contains all recordings of that program inside that "folder", sorted into reverse recording date sequence with the newest one presented first.
Again, no 3rd-party plugin required to present thumbnails. It's automatic from the program data provided to Microsoft by Zap2it and then out to my WMC system from Microsoft twice a day.
(1) Highest-level folder view, alphabetical by program name:
(2) internal within a folder, reverse chronological sequence (newest first):
Nevertheless, if your implementation of that 3rd-party plugin gave you thumbnails for your recordings that you never had before, excellent.
More importantly if something associated with its install kick-started your "resume" behavior to now work as it clearly should have been working before, even more excellent!!
Regarding that 3rd-party plugin, are you describing an additional "album art" cover that appears in the deep-down "synopsis" information screen when you push the "i' (information) button on the remote? I do see that for movies I've recorded it's just a generic icon of a disc in a case, perhaps implying this was a "movie". But for sure it's not a meaningful picture associated with that movie.
For TV recorded programs, that "program details" shows a canned photo that looks like a promo shot for that show.
But for movies it's just the generic disc-in-case icon.
Is that what this plugin provides? An "album art" cover for movies? You can give its name here, don't worry.
So you do or do not have the same high-level program thumbnails in "Recorded TV" that I do, through your HD Homerun setup?