Ron,
As far as I know the warning is there to inform you there might be issues with the black bars showing at the edges of non conforming sizes.
I, like you, use a combination of various sizes in all my projects. If I dont want the black bars to show, I resize the clip/image to fill the complete screen. I, personally, do not crop images to fit the 16:9 aspect ratio before using. I just place them on the timeline, resize to fit the screen, then move the image around to get the shot I want.
I have never experienced any problems using this approach.
Hal
OS - Win11 Pro, Alienware R13, CPU - Intel Core I7-12700KF 12 CPUs), 16g DDR5 4400 RAM, Video - Geeforce RTX 3080ti 12g, PD11 & PD365
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