Is the route Germany - Beijing - Poland eligible for the 144h Visa-free transit

Hello,
I'll be travelling on Business to Beijing, arriving on September 18 and leaving on September 22. My flight itinerary is Frankfurt/Germany (FRA) to Beijing Airport (PEK), and back from PEK to Warszaw/Poland (WAW). Is this itinerary eligible for the 144h free Transit?
Our company's travel agency advised me that it would not be eligible, because both Germany and Poland are EU member states. Is that correct? Is the EU (European Union) considered as 1 Country?

Thanks in advance for your Feedback!