It is an annoying little quirk, but after the latest update, I can not click and drag the mouse to change a value in a menu such as document size, item location coordinate, etc. The value window must be double clicked to highlight the numbers to be changed. Why?
Sorry to hear about your experience. Would it be possible for you to share version of OS & Illustrator? We'd also appreciate if you can share a small video of your workflow so that we can understand your concern better & assist you accordingly.
Adobe Illustrator Cloud subscription - updated from 2020 to 2021
You can see in the video when I create a document and try to set the size, in the older version of Illustrator I could click and drag the mouse to highlight the value. But now with the new version of Illustrator I have to double click to hightlight the value. Very annoying because click and drag has always been the way I highlight anything in adobe.