Workaround,
I had to find an easier option since this has been killing my workflow at the office.
This workaround doesn't fix the problem it just makes it a bit easier to open, edit and drag and drop files in a folder.
I hope this helps a little until MS updates the critical error. Seriously, this is the biggest set back they have had in years and I'm so disappointed in them.
So here we go...
open up your Outlook in MS Edge browser, not the desktop version.
once open click on your attachment in your email.
click download. Yes I know you are saying "wth" but bare with me
The downloads box from the Edge browser appears in the upper right corner.
Click open file and it will open in adobe reader/acrobat. If you have system viewer on, it will open pdf in separate window.
from there you can highlight and add text on pdf before saving.
Also, you can drag and drop the pdf file in the browsers download box to any file explorer folder on your laptop/desktop with no problem.
This will at least save a few steps.
Peace and Blessing