Clip Label Colors change back to default blue by themselves!

Hi! I have a recurring problem in Premiere Pro: I label all my clips in the timeline with different colors before I start cutting a scene. And at some point, during the editing process Premiere Pro suddenly deletes the colors i assigned to the clips and they are all default blue again. I don't understand why and how this happens. I always have to start marking them again to know which clip is what. This takes hours. Can you tell me why this happens? 😞