Your experience is consistent with the report here:-
http://www.flyertalk.com/forum/26797933-post237.html
EY call center will only look at their own charts, not the charts of the partners they are booking on. Although it may appear entirely illogical, the EY chart only indicates an Off-Peak economy award on US->Eur, not Eur->US.
The chart does state returns are twice the one-way cost. That means a return Eur->US is always 60K, whereas its possible to get US->Eur return for 40K.
Anyone starting their journey in Eur during an off-peak time might be better to book 2 1-ways, depending on the per booking fee.