Hard to say without seeing your data. 

I would suggest try one of these options
 1. Export data as DICOM. Since Philips has deprecated PAR/REC this seems wise, and would provide archival quality datasets.

 2. You are using the latest stable dcm2niix release. However, there are a few minor changes to the PAR/REC conversion are in the development branch. I would compile the latest development commit. If you use Windows, go to the dcm2niix github page, select the "Development" branch, click the green AppVeyor button and click artifacts to get a compiled version. If you use Linux/MacOS:

$ git clone --branch development https://github.com/rordenlab/dcm2niix.gi...
$ cd dcm2niix/console
$ make
$ ./dcm2niix

3. Follow the advice provided and try the outstanding dicm2nii
  https://github.com/xiangruili/dicm2nii