Hey!
So this eventually sorted itself out but the issue was that under the metadata settings, it wasn't finding the DB entry. The search kept giving no results.
When I went back the next day and tried searching the metadata game entry again, the entry was found and then I initiated "download missing media" option and the box art showed up in my collection.
Not a huge deal but all I can see is that leaving the device (Retroid Pocket 5) off for the night and retrying a day later fixed it.