3D picture import sometimes has wrong aspect ratio. Sometimes a full width side by side 3D picture is interpreted as half width even though I select full width. When this happens setting the width/height manually does not work properly. Older version of Movie Edit Pro worked correctly. This happens in the 2020 version of MEP.
It is a display problem. When I click on the image with width/height clicked, the displayed image is too wide, but the frame is the correct size. This makes editing several pictures and text difficult. If I unselect the image, view a different image by clicking on the time line and then go back to viewing the original image, it is displayed properly. So you need to look at the display section.