Ebay rejects listing bc one photo is too small??

Two listings rejected despite pass error check. The so-called "error report" actually has three items. Two are labeled as "notice", with some jive I won't even go into unless necess. Third in red is "Failure". "Buyers like large photos ... " aiidn. "Recommends at least 500 pxls."
One of the 2 photos is abt 450 bc it is the end of a box and was cropped accordingly. The other is much larger. So ebay rejects bc one is too small?

Now to the hair-tearing part. To make sure there was nothing else in the legacy listing at fault, I switched to "create similar" from a listing that posted successfully. I had to change title & price, & replace photos*. [*not that easy w Auct quirks in photo window.]
Lo & behold it worked for one of the two.
But then I tried CS on that to post the second one. This failed & got same errors. I went back to the prior posted listing which worked the first time, CS, but now this failed also.
What the heck? There is something in the photos that triggers this error? Sometimes but not always?