Sounds like you need to change it from AD mode to ADSR mode which is the button to the left of the pitch envelope.
The pitch envelope length is also changed by the amount to make it snappier or longer pitch change.
The Tempest does not record polyphony, that is to say you can only record and playback one note at a time, the workaround is to record into and play back from a DAW or any externalmidi sequencer that does record polyphonic sequences. Or play live.