Returning from Asia yesterday(BKK-NRT-SEA), I had seat assignments when I booked tickets months ago. Had checked probably 10 times since I booked the ticket, all good. I had bulkhead/aisle first row of E+ on the 777 for BKK-NRT and NRT-SEA. Waiting for UG to clear which it did not by check in.

When I actually checked in the res system had moved me to middle seat of a random row halfway back in the plane and some other randomw seat for the next leg. My old seats were not available to change back.

Fortunately in the end, both legs cleared on GPU. Scary none the less thinking of losing your E+ aisle/bulkhead seat randomly at t-24 checkin and being placed in the middle seat of 5 seats in E- with no explanation.