This is interesting; definitely sounds wrong... @kkosev reported seeing this exact behavior on an earlier firmware:
I haven't been able to reproduce any reset/join failures recently, though l had one instance where an Iris V2 contact (which turns its blinking blue light to green on successful join) appeared to have paired and then went back to blinking blue again when I had left Zigbee joining process running. Tried to reproduce and couldn't but definitely saw it once.
