After upgrading to macOS Mojave, I suddenly cannot select text to copy anymore in Preview.app.
I can highlight as normal and when the highlighting tool is active, I can select text but it immediately gets colored yellow once I "release the mouse" (before the update, there were two ways of coloring text yellow: 1. Highlight text (making it blueish) and click the highlight tool, or 2. Click the highlight tool and drag and select it).
Edit: It is as if what has happened is that I can no longer see which text I am selecting. I can apparently select text and copy it and I can paste it into other programs, I just cannot see what text I am selecting while doing it.