NEED HELP! Warp Tool Problem

Just installed CC 2020 and now having an issue with the Warp Tool...specifically when using the upper and lower ARC function, including the ARCH function too. Normally I will open a png image, apply the changes and click the select (the checkmark) and all is well. But now each time I do this, a thin black vertical line appears across the image?

Any suggestions as to what I can do to prevent this; I have 350 images to process, and I've been doing this for years with no issues until now. Please see the pics I provided showing the original image before the transformation, and what happens after. The black line does not show at all during the process until I click "OK".