Artifacts in images after exporting to JPEGs

[Tinkerbell92]

For the last few weeks I have been noticing random large square artifacts in my images after I jave exported them from RAWCR3 to JPEGs. In a gallery of approx 90 images sometimes there is up to 5 images that are damaged and need to be re-exported. Once re-exported they are fine. 

[johnrellis]

1. Set Preferences > Performance > Use Graphics Processor to Custom and uncheck the option Use GPU For Export. Does that avoid the problem?

2. Do the LR menu command Help > System Info and copy/paste the entire contents here so we can see exactly which versions of hardware and software LR thinks you're running and important LR options that are set.