I had the same problem initially. I found that flicking the connection only made it worse; the bubbles turned to a sort of froth that made the change take a long time and use a lot of insulin. I found that the best method, for me, is to (1) rotate the tubing so that the bubbles center in the connection and hopefully make them move along and (2) put tension on the tubing and pluck it to help move the bubbles.
Hope this helps!
