As an update to this thread...

I had originally waitlisted on January 27 for a round-trip.

It then occurred to me that perhaps the waitlist would not clear unless BOTH inbound AND outbound had seats. So, I then waitlisted a second booking for one-way flights in each direction. Those second bookings were made on January 29.

Today I received an email and SMS indicating that the waitlist had been cleared/confirmed. I had quite a long time to confirm/ticket it (April 2).

I contacted MPC, and learned that it was the one-way outbound had cleared. The roundtrip was still waitlisted.

I booked the one way, and have a J seat in the mini-cabin! :-)

(In the meantime, I have been playing "whack-a-mole" looking for reward availability. I checked this morning and nothing was available.)