scsov509, I don't know if this proves the cure but I found that by pushing the magazine upwards from the bottom with my finger and releasing the slide slowly or quickly, the bullets feed every time, indicating the magazine does indeed possibly sit too low.
I assume this is the problem but I don't know how much vertical play should be in the magazine. Using calipers I measure .030" of play and you mentioned you also have the same, which makes me wonder if that is not the problem. If not, at least I'm getting closer.