When recording a loop with ANY looper that does not let you pre-define the length of the loop, you need to define the end of the loop by pressing the footswitch a second time. If you simply stop playing, silence will be recorded until the looper reaches the end of available time.
Yep. You have to both start and stop the loop yourself. One click to start, another to end.
One click to start, another to end.
And, doing that with precision is the essence of the Art of Looping 
Make sure your start with an "empty" loop. Otherwise the length of the loop might already be defined by an earlier recording.
If you press the Record / Playback / Overdub button the first time, it starts "recording". Let's call it time 1.
If you use Record / Playback / Overdub again, it sets the end of the loop. Let's call it time 2. If you had pressed shortly, "playback" started from time 1 to time 2. If you held the button, it's playing back from time 1 to time 2 and recording ("overdubbing") at the same time.
The very first recording sets the length of the loop.
