Pixelated Images in Develop Screen

[NickyG1885]

Hello! I'm very new to Lightroom and things were going ok up until last night. I was practicing some edits and imported a few new images and when I click on them to bring them up in Develop mode, the image appears to never fully load. It remains extremely pixelated and I can't work on it. The first 2 images in my filmstrip are totally fine, they load perfectly and are clear. It's just the last 4 that have this issue. Any help would be greatly appreciated. Thank You! 

[dj_paige]

What is the size in pixels (width and height) of this image?

Is it blurry/pixelated when you change the zoom to 1:1?

How do you know that the original image, as shot by the camera, is sharp?