Video Vertically Stretched Following Rendering

[default2kr1ky20fuei]

Hi. I'm editing in Premier Pro 15.2.0. I'm having an issue where my video, after rendering in / out, becomes vertical stretched. If I go back into the clip and edit a feature e.g. position by 1 pixel, it shows the clips as a yellow unrendered clip and with no vertical stretching, which is correct. If I again render this clip in the timeline, it will become stretched out again.

I initially thought this may be some funny-ness with warp stabiliser, but it also happens for clips which don't have WS applied.

You can see my sequence setting in the screenshot. In the other two screenshots you can see what I mean by "vertically stretched". What's stranger is that it only happens to the bottom half of the image - if you compare the top you can see that vs. the overlay margins, it's not affected. You can also see it with the adjustment layer in the first screenshot which at a 12% croff offset on both the top and bottom results in the bottom being lower than the top as shown by the guide overlays.

Thanks for the help!

[Andy 1968]

It looks like you have a 21:9 video in a 16:19 sequence. You can do do that but you have to make sure the mathmatics are correct at export. The video at 1:50 might be helpful.