Yep I had a similar experience today.
I just booked AKL-IAH in PE end of July which cleared immediately (after calling them and asking for R class availability in J) but for the return flight from LAX- AKL on NZ5 in August they could see R class available but had to send it off to a separate team to get it cleared and they assured me it will be cleared on Tuesday due to the long weekend but the agent I was dealing with held a seat for me in J.