This one's pretty easy to reproduce:
1. Switch to tape mode
2. Record a sample of a few seconds or so using a drum or synth part, it doesn't matter
3. Shift+repeat to select the whole loop
4. Ensure that position 0:00:00 is the in point
5. Play the loop, loop repeats as normal.
6. Shift+play the loop, when the tape head reaches position 0:00:00, it repeats the tiny sample at that position rather than jumping to the end of the loop.
7. Increment the in point a teeeny amount forward, like a few milliseconds, and the reverse loop works just fine.