Jamming may occur if you press the release button on the connector before the electromagnetic lock is released.
You can determine whether the electromagnetic lock has been released by checking to see if the red light has switched off on the handle of the connector. Once the electromagnetic lock releases, tap the connector with something, for example, a phone, in order to release the jammed latch.
Once it has been knocked free, you should be able to remove the connector.
Refer to the video below for a step by step explanation.