How are stopovers defined with the companion pass?

I searched for a round trip flight and then picked two options. The return flight had two connections, each with about 6 hour layovers. Does having a connection >xx hours count as a stopover? Or is it just having two connections that causes an issue?

The system marks the flights as valid and shows appropriate companion fare charge, but then produces an error:

"The Discount Code entered is valid for round-trip or one-way travel, however the itinerary selected exceeds the maximum stopovers. Clear all selections to choose other flight options."