I believe they worked together very well actually, but my grandfather could apparently be far too harsh with his feedback. Asimov complained bitterly in his autobiography about this, but also gave him some grudging respect.

I think my grandfather thought he was helping by pushing writers really hard to do their best work. He probably was right to some degree but clearly took it too far at times.

From the contents of Galaxy, and the output of Asimov, I have to say I agree with your grandfather 100%.