Preview app showing PDF as black and PDF Finder window icons glitchy

For about a year now I've occasionally seen PDF docs showing as black, both in the app and in Finder as a well as Pathfinder. I installed Adobe Acrobat Reader as a work around which worked but found the interface cumbersome for my needs.

So I recalibrated the display following a tip. That fixed it, for some strange reason and so, having noticed a few people seeing this issue (for quite some time now- years in fact) here's my 2¢.

Possibly associated is the feature whereby the file icons in windows containing PDF icons in Finder flash like they're on a faulty circuit. That's been going on for quite a while too. Any tips welcome.

https://tidbits.com/2018/01/30/fixing-pdfs-whose-pages-render-as-black-rectangles-in-preview/