Sorry if this is a near-duplicate report. I thought I submitted something yesterday, but nothing shows up now.
std::istream& operator>>(std::istream& i, gnssRinex& f ) from DataStructures messes up reading the first data record. After reading the header, the loop at line 3077 reads to the first epoch line. Then the statement: strm >> rod; at line 3124 winds up immediately reading to the next epoch line. This happens at RinexObsData.cpp:204. Thus, the first data record (following the first epoch line) is entirely skipped. This bug is in at least version 2.0.