Trying to crop video but black borders are added on export

I have a 1920x1080 video that I would like to crop the sides from, leaving a square 1080x1080. I made a custom video mode that is 1080x1080. When I use the Crop filter, I have to make the width about “600” to approximate 1080. I used the YouTube export preset with the video resolution set to 1080x1080. I export to mp4 and end up with a black border on either side of the video which brings the width back to 1920. The file properties in Windows 10 says that the width is 1080 but when I play it back, it clearly isn’t.

When I use video mode 1920x1080 then I get a square video with black borders on all four sides!

Can anyone please advise on how to export a square video without black borders? Also any idea why Windows 10 file properties and MediaInfo say that the video is square but when I play it back in VLC or Windows Media Player or upload to GIPHY (a website that converts videos to GIFs), I get these borders that make it clearly not square? Thanks.

It sounds like your video mode is actually wrong or at least its aspect ratio or the aspect ratio in export. If you are changing something in export - resolution or aspect ratio - you are doing it wrong. This might help