The most likely explanation, IMHO, is that Qenos is having...

The most likely explanation, IMHO, is that Qenos is having trouble securing ethane at a viable price.
If STO can supply the LNG plants with a gas mixture that includes a few percent of ethane they can probably make more profit than splitting the ethane out and shipping it to Qenos.
I don't know the composition the LNG processors demand, but overseas LNG can include as much as 9% ethane:
http://www.beg.utexas.edu/energyecon/lng/LNG_introduction_07.php

Because EPX isn't party to the supply negotiations, holders are left in the dark, doubly so when Qenos can't supply a consumption forecast past December.

Hopefully, they will conclude an agreement for a larger supply shortly.