We have clarified our understanding of it many, many times–we do not understand it in the way the EO Chuches understand it to be heretical (and which we agree with them that it would be!): that is, two principles or two spirations. The problem is, the EO dogma has basically become Rome is wrong no matter what.
Giorgios Scholarios, an EO Patriarch who was more open than most to Western thought, said the following about our explanations:
for as long as they profess the Filioque in the Creed, even though they deny ten thousand times the Dyarchy (alt. trans; the two principles of Godhead) and Sabellian-like teaching, and other such things, or even should they renounce or state their intent of renouncing their teachings at some point, but still retain the Filioque, they still remain what they are.
It also doesn’t help that many of them just plainly reject many of the Latin Fathers who enunciated this doctrine in the same way. For example, their saint, Mark of Ephesus, said “The words of the western fathers and doctors, which attribute to the Son the cause of the Spirit, I never recognize.”
Sadly, there’s no reasoning with that kind of attitude.