I added an Arkansas Black on M.111 to our camp orchard a couple years ago. Like you guys, few blossoms, no fruit so far, but it is still young. However, since adding this tree, I see Cummins mentions that this is not a very productive tree. Also, Pomiferous says it produces only light crops biennially.
However, I am not too discouraged because I have a mature Arkansas Black (30+ years old) on an unknown rootstock at home that is very productive and holds well into December. Good things come to those who wait… impatiently!!