I imported a video straight to my Final Cut Pro (by clicking and dragging onto my timeline) and it's just a still image when I press play. What am I doing wrong?

You can’t drag it from the Photos application itself. You might e able to Acces it from the Photos browser in FCP. The media had to be stored locally and not in the cloud. It would be best if you imported the video directly from the phone into FCP and not through Photos.

It should work, so you are probably doing something wrong.

You need to give as many details as you can about what you are doing, the project specs and the specs of the video you are trying to import. Also where is this video . . . on the desktop, a separate hard drive or somewhere else?

Are you certain it is a proper video and not a jpeg etc.?

How many layers of video and audio at high resolution can you play simultaneously from the cloud? Mostly less than one.