Ooooo, doggy...this thing sure gets complex. Apparently the Lutherans did lay out their doctrinal beliefs before the Orthodox. The Orthodox simply had issues with them. An interesting article from the Orthodox center is Luther Had His Chance. (Love that title.) The article refers to the Augsburg Confession which shows the differences in belief.
What I do find puzzling is why on earth Luther would think he would have anything in common with the Orthodox and why he didn't anticipate the Orthodox reaction? The Augsburg Confessions plainly challenge many of the Orthodox beliefs just as much the Catholics. They sound somewhat Reformed. (It was Calvin who laid out the Protestant's systematic theology-not Luther.) Did Luther think the Orthodox would simply read the Confession and say, "Yep, you're right. Guess we've been wrong all these years."? If things only worked so easily, I would have everyone here singing, A Mighty Fortress Is Our God.
The articles I look through do not address these questions. I can only surmise that these were dangerous times for Luther and Protestants in general. Perhaps they were naively looking for some sort of support. They certainly didn't find it with the Orthodox.
I don't have the sources ready to hand, and am in a hurry during a break, but I'm pretty sure that the exchange between the Lutherans and the Orthodox happened after Luther's death.
The Reformation had by that point started to harden in its positions, and was really not in a position to be influenced by the Orthodox. The motivation seems rather to have been that the Tubingen theologians thought that they were going to enlighten the East. Ex Occidenti Lux.