iMovie file export swaps '/' and ':' in the filename When I export my iMovie project to an mp4

File > Share > File (iirc)

And name it "Tacos w/ John" for example, the file created is "Tacos w: John.mp4"

But if I name it "PROJECT: Yi", it saves to "PROJECT/ Yi.mp4"

Why?
They are reserved characters. You can’t use them you need to think of a different delimiter. IE. Tacho-John.mp4