Can't drag more than one clip to the timeline

I'm having problems with the updated version of Premier Pro. After making 25 min of movies with really many clips, graphic elements, pictures, etc. I suddenly can't add more clips to my timeline. Or that is, I can pull the audio part of the clip over, just not the image part. I have tried to create a new project and here I can add 1 clip that works normally with both sound and image. But when I try with 2 or more clips, it is crazy again. Only the sound part can be pulled. I've tried to re-encode various clips into Quicktime format with Adobe Media encoder. It does not help My PC is new. My graphics card NVIDIA GeForce RTX 2060 has the latest updated drivers. I have now installed an older version 13.1.5 and here the program works fine again.

It would be great to be able to use the latest version of Premier Pro, so do any of you have a clue as to what might be the problem?