When this issue presents it may be uncomfortable- the pump will suction the breast, but not release the suction, expressing the milk. Luckily, most cases of this happening are simple to fix!
For the suction on your pump to work properly, the suction loop between the diaphragms, valves and breast need to be closed. If there is space between the flange and breast, or the valve is not sealed, the suction may get "stuck". You will notice the diaphragm inflate to the top but not lower again.
To troubleshoot the issue check the following:
1) When was the last time you measured your flange size? This can change naturally overtime and impact your pumping session. If you haven't measured recently, check out the article here and contact us if you need help finding the flange size you need!
2) Try replacing the valves! If they are over a month old they may need replacing. If the valve no longer closes flat under the suction, the loop is not closed, this can cause the diaphragm to over-inflate.
3) Contact us if the valves have been replaced and your flange size is accurate. We can help from here in getting you a solution for the issue.