After hours of searching, I finally figured out that my problem was due to the "Microsoft XPS Document Writer" being turned off in my installation of Windows 11.

To resolve the issue, I searched at the bottom of my Windows 11 screen for "run." I then opened the "Run App" that came up under my search and typed "optionalfeatures" into the Run App. A "Windows Features" window then opened and I scrolled down to "Microsoft XPS Document Writer" and checked the box next to it. I then pressed "OK" and voila I was able to start creating PDF Invoices again. I attached a few images of the process here for reference.