Overlay - LiveView vs image file

Using SS5 with Nikon D5300 on a PC windows 10
I ran across SS5 to use for Stop Motion animation and tried some tests. Concerning the nionskin/overlay, I had an issue where the LV did not match the previous image captured.

on a setup, not touching the camera or subjects, I shoot an image and then look at LV.
In SS5, in LV, ‘transparency’, sliding between 0 (file) and 100 (LV), I can see a size difference in the image.
In the camera, I turned off, ‘auto distortion’, which helped but didn’t eliminate the issue.
In SS5, LV, I adjusted the Brightness Boost to match LV vs file but also didn’t eliminate the issue.
in SS5, I tried multiple ‘Quality’ settings, with no improvement.

In the SS5 LV options, enabling ‘LV statistics’, it shows; full sensor, 640 x 424 jpeg.
I’m wondering if the culprit causing the non-match, LV vs file, is the ratio between the LV sensor and image file?
Thanks