Yes, I've noticed the Delta calendar does not work correctly....
I will try to provide a
condensed version of last week's experience with the Award Ticket calendar....
Spent 3 days trying to match up and book 2 itineraries --spouse's + mine-- multi-city, 45000 miles each booking. I was amazed at how broken the calendar is; I tried 2 office computers not on the same network as well as my own home PC and kept coming up with different flight options each try. Cleared the cache, erased the cookies, etc., with no success. This made me crazed.
Phoned Delta and was put through to 1-800-I-Don't-Speak-English only to be told it is my computer's fault. When I then asked to speak to a Supervisor the agent said he IS the supervisor and in charge of everyone else and could not help me - not his problem but mine. Gimme a break.
After much conversation with this same guy, he conceded and booked my itinerary to match spouse's, put the reserv. on hold, and told me no fee 'this time'

This agent said to be sure to redeem my itinerary online through my account which of course didn't work after numerous tries.
Phoned back on Day 3 and was finally able to convince another agent that the problem lies with their system, not my computer. That agent completed the redemption over the phone and I was not charged a fee.
Adding to the frustration: anyone I spoke to made it sound like they have never, ever encountered this problem before my phone call.