My bad lol. Well I'm not sure what's exactly causing it. The total file size or the bgm size. Have you tried putting just those two themes in shuffle and seeing if it loops or not?Ahhh ok. Could've been a bit more specific than "error out"
I had 5 themes in that shuffle, and all the others worked fine (I checked them all) so I don't think this is related to having too many. It's just that the bgm for that theme is too big.
And by total file size I mean by all the themes together in the shuffle queue.