I have not visited this forum for many months but it appears your question has not been answered fully, so this belatedly is what I have discovered as a Pod user for 2 years. The problem arises because it is difficult to remove all the air out of the syringe prior to filling the pod. The shape of the syringe at the needle end is not ideal and captures bubbles that are not easily seen - and they are difficult to remove properly. When drawing the insulin into the syringe from the vial do it slowly, giving time for the liquid to pass through the narrow needle.. You will no doubt have seen the large bubble that always collects at the top of the syringe after some insulin has been drawn in, and you need to push that bubble back into the vial. But you need to do this carefully. While keeping the syringe tightly attached to the vial above it, angle the syringe (and maybe tap it) so that as much of the bubble as possible is positioned directly under the needle and slowly press the plunger and watch the bubbles go back into the syringe. When they have stopped, GENTLY and SLOWLY draw more insulin out into the syringe. I emphasize this because if you do it too quickly you will also get small bubbles coming in from the bottom of the plunger (because the piston is not air-tight). If for some reason you get any bubbles from either end of the syringe, squirt them back into the insulin vial, as just described.
Finish by slowly pulling the plunger all the way down just past the 200 mark. Remove the needle and gently quirt a small amount out at the top end (I catch it in a tissue). You should be able to do this with the syringe still filled up to about the 200 mark.
Now when filling the pod - Ensure the needle is pushed into the hole firmly but without exerting too much pressure. (I leave the pod in its container and, with a finger at its centre, hold the pod firmly in position). SLOWLY press the plunger to fill the pod, but do not plush it down completely. You should leave a little insulin at the bottom where there is a mark which exists as a guide. Although this may seem illogical because one expects bubbles to appear at the top, in reality the shape of the syringe by the needle seems to capture bubbles that fortunately do not get pushed into the pod.
Excuse me if I appear to be telling you how to suck eggs but if you do this carefully I can assure you that your pod will start working without the delay. While I have made this a lengthy explanation, the pod changing process will take less than 5 minutes and is much easier than with any other pump that I have tried.