The problem lies with how the MyCloud web portal or it’s corresponding code within the My Cloud firmware is handling the MP3 files metadata tags. Assuming of course all the files with missing album covers are encoded for MP3.
Couple of suggestions. First, check the dedicated EX2 Series subforum to see if others with that device have experienced similar problems (if you haven’t already).
Second, try either reencoding the audio file with the missing album art to ensure it’s in MP3 format by checking what audio encoder was used on the MP3 file(s) that do show the album art. Could be a problem with the web portal not liking the audio encoder used to the create the media file.
Third, try using a different program to edit/create the metadata tags if you haven’t done so already. The free MP3Tag (https://www.mp3tag.de/en/) is one popular metadata tagging program as is Media Monkey (https://www.mediamonkey.com/).
Lastly, read through the unofficial Twonky FAQ if you haven’t done so already. There may be suggestions in there to help with your issue.
I will look on the EX2 subforum (I have also moved this post to that subforum). I used mp3tag on all the files (apart from the BBC one), and its odd that only one appears. You mentioned Twonky, but I’m not sure if you saw my screenshot as that displays the images perfectly so I don’t think it has anything to do with that.
Thanks for the reply. I think you got the wrong end of the stick. The BBC Podcast files are fine, its my other files not working.
I tried to log a support call as you suggested but just get this after filling in the form, and lost everything I had typed in! Is there an email address I can use?