I upgraded to Catalina from Mojave. Now I cannot merge video clips into one video. Previously, I'd open the first clip, and drag 30 other clips into the original window and Quicktime would merge them. Great for sports cliips where I stop the recording while play is stopped and then I can connect all the 30 clips together into one video. After I upgraded to Catalina, I cannot drag and drop the clips into the Quicktime window. Anyone else have this issue? It's quicktime 10.5 on Catalina. Thanks.