I added some new discs this week and added artwork (named ‘folder.jpg’) to each of 21 folders (discs).
In each case, the artwork is rotated 90 degrees CCW. I have viewed/edited them in a number of apps (including PhotoShop cc2018) and all show the orientation to be correct.
Can you upload a few pieces of art to Dropbox or similar and drop us a link? I think the fastest way to understand what’s happening here will be to look at the media directly.
I’m unsure what to make of your response. As per the OP, the files are in each album and named folder. I attached one example of each (of the two) jpgs directly from the folder on the server. I also attached a screen shot of the Roon server display of the images. They are clearly rotated in the screen shot.
I have continued to dig on this - in the absence of any support - and discovered the following:
The image files were (inadvertently) saved at about 3000 pixels square. This is the only oddity that I can find, and having reduced them to a more sensible size, it seems to have fixed the issue. I also added the image to each mpg file.
It would seem to me that there is a possibility that Roon is not checking and rejecting large pixel dimension files.