Resolve adds a black border when rendering

I'm working on doing what I can with some old video files that only exist in low resolutions, as low as 320x240. The intended workflow is running Neat Video on it in Resolve before handing it off to Topaz Video Enhance AI and finishing it back in Resolve. Getting step one to render properly has proven more difficult than I expected.

Whenever I start rendering black borders are added at all sides of the image. I've set a custom resolution to match the original file everywhere I can find it and Resolve still adds a black border. Searching the web for this issue told me to change image scaling/anti-alias edging to off but that had no effect.

There is no black border when previewing the video but it is always added as soon as rendering begins.

It seems like there has to be a way to disable all of the scaling and other resolution modification Resolve can do. How do I force it to use a video's original resolution?

Do you see that border on all sides? DR has a lower limit of 256 pixels, so you should see it only at the bottom and the top.
And then, VEAI can also handle noise to some degree, I'd try to upscale first and then check how much NV you really need.