This one is consistently reproducible here, but I'd appreciate a confirmation please in case it's unique to me.
I think the illustrations are self-explanatory, but the bottom line is easily stated: when an object is imported but then replaced with one of the same name after being edited externally, its aspect ratio is corrupted by MEP.
This example shows a landscape JPG which is imported, deleted, edited to portrait format and re-imported - when it becomes distorted. Only in those three recent MEP versions. Surprised I haven't noticed it before...
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Terry, East Grinstead, UK