i usually have lot of problems when trying to buy awards flight with aeromexico/airfrance/ mixed legs
it charges my card, in one case it took my miles, but then i get error
finaly i had to book trhought the chat
had to pay again, miles deducted again with the promise of refund
after 3 days nothing refunded, so i chatted again and this time the miles appeared in a few minutes, but the double credit card charge still not refunded

Another was first leg latam second AM, no miles taken, no credit card charged, but trip appeared in my trips (with no ticket)
After few days the first leg disappeared , second still in my trips

Today I was buying an award LIM-MID , two legs AM, got many errors when looking the different dates
Then opened incognito browser in chrome, and it worked perfect, ticket bought without problems
I hope that Delta looks in their error logs to see what happens...