After a little more digging, it looks like NPR is using software that writes invalid MP3 IDv2 tags.
The tags say they're v2.4, which is fine.
However, when presenting the size of the picture frame, they're not using a 28-bit sync-safe integer like the spec calls for. Instead, they're using a standard 32-bit integer. This causes MC to only (correctly) see 11 of the 22 available KB of the picture.
The spec is here:
http://id3.org/id3v2.4.0-structure The frame ID is followed by a size descriptor containing the size of
the data in the final frame, after encryption, compression and
unsynchronisation. The size is excluding the frame header ('total
frame size' - 10 bytes) and stored as a 32 bit synchsafe integer.
There's not much we can do, because if we switch to 32-bit integers here, it will break support for correctly saved tags.