Topic: Main images aren't showing at the right size

I know I have to be missing something somewhere... but the images are loading at weird sizes.  They're all rectangular, and set to the same dimensions, yet the horizontal images load 565x335, and the vertical ones 375x505.  Neither maximum dimension is correct...

I have the maxImageWidth & maxImageHeight set to 510 and the imageAreaWidth & imageAreaHeight set to 510 - in theory one dimension has to be 510px, 'cause it can't be larger or smaller than 510px, right?

Is there something else I can do?

Any suggestions are appreciated - at this point I'll try anything, cause I feel like I've already tried everything...