I’m guessing you need to change your canvas view to “image & wireframe”
At the top of the canvas there are 3 buttons. The far right button is a dropdown menu of view options. Set that to “image & wireframe” then, if a clip is selected, and the playhead is on that clip, you can drag that layer around the canvas.
If this isn’t the problem let me know.
Another tip. Beware the “W” key. This is set by default to toggle between “image” and “wireframe” view modes. I can’t tell you how many times I accidentally hit this and spent ages wondering why I wasn’t getting playback in the canvas.