Aw, poor baby. I had a German Shorthaired Pointer years ago, and he too was very timid, for no apparent reason. He would also have anxiety with basic training commands...we eventually learned to teach him with hand signals, no voice. Once he relaxed, he was an absolute breeze to train, and he was brilliant.
As far as Ivy not being treat-driven, have you tried tiny bits of boiled chicken? That usually motivates.
Good luck with her, she sounds like a sweetheart.