Multi-Instrument Crossfade or equivalent?

Sorry about that. Too hasty a reply. Try this:

  1. No fades on the multi itself.
  2. Keep the multi Async.
  3. Set the loop region to the exact length of the loop minus the crossfade length you want.
  4. Keep the multi slightly shorter than the loop.
  5. With the multi selected, right click the Volume knob in the deck (bottom left) > Add Modulation > AHDSR.
  6. Set the attack and release to the desired length of the crossfade, and push those curves up to keep equal power.