When you create an 4-beat auto loop by long pressing the Loop IN button on a Pioneer controller, then the loop start is set after 2 beats. It should be set to the beat where you started pressing the button.
Example timeline with beats:
Beat 5 <= press and hold button IN/4BEAT Button
Beat 7 <= this is where the 4-beat loop will be created and where it will start
The 4 beat loop should be created from beat 5 to beat 8 (the second bar).
When the user presses the Loop IN/4BEAT button a MIDI message for loop in is sent. After a short time the long press is recognized and the MIDI message for auto loop is sent. But this auto loop needs to start “backwards” when the key has been pressed initially.