The delay is enabled by tapping the button on the XY-pad.
The above image shows the various parameters at different positions. The delay can be used to loop segments as well as perform a normal delay with feedback.
The delay line is only active when the icon is bright. Only when the delay line is active is its buffer updated. That can lead to some unexpected effects because the data in the delayline is not necessarily what one expects at a certainpoint. E.g: after seeking to a new location. Often, the delay line might be empty, and requiring it to loop then will just not work out very well.
Therefore it is important tot prime the delay line before using it. That is done by placing the dot at a no-feedback position and length of 1 bar. (bottom right), enabling the delay line, after which the buffer will fill up. Once that buffer is full you can switch to any position on the pad.
This effect can of course also be used to your advantage. It is for instance possible to prime a delay line at bar 50, turn the delay line off, then move the xy-dot to the top right and enable the delay again at bar 90.