Yes, tried that with no luck. Examined the Output Options (under settings) and "Preserve cover aspect ratio" is unchecked. Of course if it WAS checked it should add borders, not crop. It should NEVER crop as far as I can tell.
I uninstalled Calibre back to v3.37 but my reader reacts the same way to larger covers on newly copied books. Older books I copied to the reader a few months back still stretch to fit.
Deleting and manually installing books without Calibre causes the same cropping.
Edit: Removed and recopied a book that stretched the cover... and it still stretches the cover.
Edit 2: Just got a new book from Overdrive today. Cover is 1475x2200 and white borders were added on the left/right to fit the screen.
There seems to be no pattern to this.
Edit 3: Digging deeper, it appears that the problem lies in the book itself. Moving some books into Calibre's editor, I see that the books that get cropped just have code for the image and not much else.
A book that resizes has <svg> code specifying the resolution and aspect ratio. There is also different code for the book that I just got that has white bars.
So it looks like how the cover is treated is dependent on the book, not the reader or Calibre. Calibre
SHOULD have more options for managing this when transferring, but it doesn't.