I did a fresh set up with 1.7.2. When I scanned my N64 Directory all the names in my playlist has a [!] at the end of the names. Having that prevents my thumbnails from showing. 1.7.1 doesn’t have this problem. Anyone else having this issue? FYI: I’m using the Mupen64Plus Core.
The [!] is from GoodN64. Could parse through them and remove the flags with…
I’ll make an issue there.
Just wanted to note it seems that the GoodN64 names differ more than just the [!]. The thumbnails seems to be using the no-intro naming.
The names for other console systems seems to be using no-intro for playlists when scanned.
If you’re your scanning your n64 games and it builds a playlist using GoodN64 naming and that causing issues with your thumbnails or vids then download 1.7.1 perform the scans and copy the N64 playlist file to the directory of your latest retroarch playlist directory.
Seems that 1.7.3 still have the same issue 
Made a PR to fix this up:
Should be fixed once merged, and the RDBs are updated. Thanks!
it would have been better IMHO that goodtools sets should be sorted and only include the romsets needed (im sure goodtools are added because of translations mostly), this should avoid most repeats and bad/overdumped roms unnecessarily increasing resulting rdb.