Good evening JLowden,
I hope your day is going well. I'm not sure if this will help, but when I upgraded the operating system on several of the computers in our office I was also unable to utilize the pdf features in FileMaker Pro. In my case, the problem turned out to be caused by the Microsoft PDF viewer. I reinstalled Adobe Reader and that resolved our problems. As I said, your situation may not be the same, but I thought it might be worth mentioning. Good luck. Have a great evening!