I recently started having an issue with images, randomly the image gets replaced by these large diagonal lines on a white background.
The images are from a Canon 5D mark 4 raw.
I've re installed the lightroom as well as my entire CC suite. The issue is persisting.
Try unchecking the option Preferences > Performance > Use Graphics Processor.
Seems to persist after unchecking, reopening the program.
This is a corrupted file. The reason it is corrupted is because of some hardware malfunction. It could be the camera card, card reader or USB cable/USB port, hard disk or computer memory.
You need to import the photos again using different hardware, and if possible using an entirely different computer, to see if you can isolate the problem.
Then it's probably you have a hardware problem somewhere in the path from the camera to Lightroom: the memory card, USB cable, card reader, hard drive, memory. If this happens on photos you've imported into LR long ago, then it's probably not the camera memory card or USB cable and more likely your hard drive or memory. If it's only happening on recently imported photos, it's more likely the memory card or USB cable (if you're using one).
If you have another computer with LR installed, try moving the suspect photos to that computer and seeing if the problem occurs there.
You can see that indeed this is a file corruption problem from the fact that the small previews in the film strip show the same artifact as does the navigator preview. If it were a Lightroom GPU problem that doesn't happen.
I just had an instance where it only effected the bottom of the image and when I moved my mouse across the different photo previews it varied between showing the full preview and the damaged preview. So the fact it's showing sometimes suggests the image is still saved somewhere. I'd love to know a workaround to retrieve images when this happens.