Yours is one of two possible occurrences with macOS Sierra. The other is also described in my report.
According to other reports, MS Office and Adobe CC behave even worse on macOS Sierra
Thank you for your post.
The link from "Benjamin Fehr" shows the "Save" button appearing instead of "Print". However, if I understand your situation, clicking "Print" jumps you into Preview.
The workaround for the link from "Benjamin Fehr" is to go to Print PDF, and select Open PDF in Preview. Once the PDF opens, click Cancel. Go back to Print and try again.
Another user ran a Recover on the file to reset the Print settings.
Keep me posted with any progress, and let me know what you have already tried to remedy this issue.
The link from "Benjamin Fehr" shows the "Save" button appearing instead of "Print".
… clicking "Print" jumps you into Preview.
Though for the first occurrence, - [save] instead [print] Button, your work around will do.
For the [Print] opening a document "Untitled.pdf" in Apple Preview, we don't know any other work around yet but run Recovering on 1 of the files.
To my experience, recovering 1 FMP file which may have inflicted the issue will solve the issue for all other files and also with all other FM-Versions(!).
I just need one other such challenge to pass the Voodoo-Certification