Seats auto assigned on PG codeshare?
 

My wife and I are traveling EWR-HKG-BKK-USM and return later this year in Premium Economy. It's all on one PNR and the BKK<>USM legs are CX codeshare flight numbers on PG. I was able to select PE seats on the CX legs at booking, but the system wouldn't allow me to select seats on the PG flights. Now a few weeks after booking seat assignments in PG's "Premier" section at the front of the A319 appeared (apparently the middle seat is blocked in the first 3 rows on this aircraft similar to BA's CE class).

Is premier seating on PG typical with a CX PE booking?

Somehow they managed to seat my wife and I in different rows (the cabins are otherwise empty on EF). Should I contact CX or PG to straighten this out?