there are know issues with Sierra and PDF creation.
interesting though it works in FMP13.
did you try on one Mac or is this constant on other macs?
i would file a bug with FMI independently - we had to move some clients back to 13 due to issues as well..
I have found this on two Macs at least, using OS 10.11 and 10.12. Yes very strange that everything works fine in FMP13 which is not the case with FMP12, FMP14 or FMP15.
There are a couple of bugs in FileMaker. e.g. saving PDF fails if the used fonts on Windows have file extension .TTF in capital letters. in lower case letters it works.
Or when using older layout styles which are no longer supported.
Anyway, you can always use MBS Plugin with DynaPDF and the Optimize command to get a smaller and fixed PDF.