Originally Posted by RealHJ

To be fair, booking CA award flights with most Star Alliance airlines is even more difficult and risky than MU with DL. It'll be booked, ticketed, confirmed, but CA will later without notification delete it's PNR, and sometimes it's never created at all, so you have a ticket, but no PNR, and thus you are not flying anywhere, and get no refund.** Many *A airlines blocked CA awards entirely. That is even worse. After a DoT complaint and management escalation UA fixed it (unlike DL, at least UA cares) and is now fine, and after escalation to Germany HQ LH came with a workaround (use "neutral availability" alternate search to find and forcefully book CA flights), but many other programs are just blocking CA entirely vs. fixing their problems or documenting a workaround.

**Same can happen with MU. At least it did it to me. Thankfully there was an open seat and I got it in the end, though I wasn't on the flight manifest due to DL/MU mess-up that had it DL ticketed but MU had no PNR/record of it (as DL does MU US airport check-in and ground ops, and one gets Delta logo boarding passes for MU flights here, so they had no choice and had to fix it), but there was no meal catered, which led to a mini-revolt in the J cabin involving pax/FAs/pilot as no one wanted to wait 2 hours for catering, and no one wanted to give up their meal on the 10h flight either. In the end FAs manually made an extra meal by taking a portion from all the other meals...so everyone got a bit smaller portion. ^ to the MU FAs on that.

So, it's not really unique to DL/SkyTeam issue, but rather an issue with mainland China state-owned airlines in particular. There's been some speculation that CA (who knows, may be also MU) will unconfirm/cancel (no notification or refund) award tickets on sold out flights, so that they can sell more seats for $$$ (or CNY, rather).

Most definitely, if it's not "HK" (hold confirmed), do not trust the ticket. It's very risky. It really is keep on trying and see if you can find anyone at DL who cares (may be if you get HIBRES and they still have the former NW customer centric spirit left in them that DL hasn't fully suppressed yet).