While transporting Mr. Faukwatt to CT, you notice the bag on…

While transporting Mr. Faukwatt to CT, you notice the bag on the non-rebreather is collapsing during inspiration and not filling adequately during expiration. The patient in on an “E” cylinder as ordered with a Bourdon gauge set at 10 L/m. The “E” cylinder is lying under the patient’s heart monitor which is also on the cart with him. What is the most likely reason for the bag collapsing?