I can try to upload some FLAC files to DropBox this evening. I
am at work now and do not have access to my computer. But I can
tell you that it has been every FLAC file that I have uploaded into
VOX that does not display album artwork. And these same files are
uploaded into the Onkyo HF Player on my iPhone and have no problem
with the artwork.
The way that I am uploading them are connecting my iPhone 6 with
iOS 8.3 to my MacBook Pro 15" Retina display with the most current
operating system and most current version of iTunes and I go into
apps on the iPhone within iTunes, select VOX and click on add and
add the individual FLAC files.