Permanent fix for broken Copy and Paste?

To get a good look at your System config. for conflicts or issues, you can run this utility http://etrecheck.com

If you need help interpreting the report you can post it here in its entirety in the "Additional Text" box in the toolbar below.

To trouble shoot further you can:

Try a SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc.

This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.

Test issue in another user (or guest user) account  https://support.apple.com/en-us/HT204443

This will tell you if it a universal issue or isolated to your user/admin account.

How are you trying to copy & paste? Are you using Cmd + C to copy the text? If so, go up to the menu bar in the app and use the option on the menu to copy it. I've had the Cmd+C not work for certain items whereas selecting "Copy" from the menu works just fine. Or you may find the Copy option is grayed out and is not available with this PDF.

Depending on the PDF app you are using and how the PDF was created, you may not be able to grab any of the text. You may have better luck with an app that can fully edit and create PDFs to grab the text you want. Or you could try exporting the PDF to another format first.