The OpenFOAM.org release of version 9 and above has made the version entry in the header of files optional. I believe the OpenFOAM.com version retains it. If that entry is missing then the files can’t be read. Since the file format hasn’t changed in years, it might be good to check file validity in another way.
I checked the code for importing the OpenFOAM results in PrePoMax (v1.4.0), and the version number is read, but it is an optional value, so the importer should work in both cases. Do you have some results where the importer fails?