continued spinning after a few videos work

download videos just fine but at a certain point, the wording that I add remains but the video is gone. I see video for awhile but then I don't . working with brand new Mac/m3 and wifi is strong. I cannot continue with express if I can't solve this. ive spent hours working to fix. I simply must use something else. I am disappointed as I have used adobe in the past and thought it was one of the best.