Help Please with Cover Art

[Budgie]

Sorry to be dumb but I have read the several threads here on cover images and still cannot sort it myself.

I have purchased some classical recordings which are only available as downloads.
In each case I have downloaded the zip file and extracted the contents into a directory which is the name of the work. In addition to the flac music files there are jpg images of the cover art (and pdf file of booklet).

These directories containing the music and jpg files are then copied to my NAS which is running minimserver. I am using Bubble DS as control app.

On only one work is the cover art shown on my control point but all three recordings have cover art jpg files in the work directory.

The only differences I can detect are the jpg file sizes. The artwork that is displayed is from a jpg file of about 270KiB. The other images are much larger, one being 1.7MiB and the other 2.5MiB. Could this be the cause and whatever it is, how can I get the artwork to display please?