Hello @Kimkrupppepe ,
It looks like you already spoke with a chat agent regarding the issue, but for visibility I also wanted to make sure it was addressed here. The Library menu tab within the email editor does cut off after a certain number of images, so the best way to find particularly old images in that sidebar would be through its search function or by changing how the images are sorted. This would also go for the Library sub-window that shows up when you Replace an existing image block / placeholder, though that generally should be able to show the entirety of your library if you keep scrolling (loading too many images can cause slowness on your browser in general between caching and downloading that much image data).