Just started using premiere pro 2021 version. I've noticed that when I place clips into a sequence on my timeline, at some point they somehow all get burned into one combination even though they are clearly different and separate clips. That means at some point, I can't extend or cut clips anymore, as footage from one clip will somehow end up on the clip next to it, so when I try to extend one of the clips by dragging it, it will show the clip sequentially next to it and not the clip I'm trying to extend. It sometimes works when I drag the clip up to the next video track, but just not when they're all on the same video track. Why is this happening? Is it a bug? Please help, thanks!