Has anyone had problems booking international flights on partner metal like KE flights?

Last month, I was trying to book flights into Asia, and delta.com gave best price for a flight with connection through ICN but could never finish the ticketing. It was always available in the search but sold out when I press pay. I then called up the PM line and even those agents couldn't get it done. Took about 1 hour to run through the whole thing. The last 20 minutes, I just let the agent do her thing.

Ended up paying a bit more for a lot more MQDs/RMDs on MU. Would have appreciated the booking work so I could save my time.

I hit it again booking AF flights and then switched to KL. This could have just been pure availability but I didn't bother to find our.