I'm trying to book a round trip in Oct, MSY/CDG transiting through ATL but I want to choose my own connections for times. I have used the multi city tool many times in the past with no problem but today I get this message:
Uh-oh! We’re sorry, but no results were found for your search. Some of our flights only operate seasonally or on select days of the week. #ROF4002_225

Is this a new thing, pushing you to select the routing they want you to take or maybe it's just too soon? I can pull up a basic round trip with those dates but it doesn't list the connections I want. Many of my preferred flights show up as bookable, just not when I try to pair them the way I want.

Apologies if this has already been addressed. I just haven't tried to do this in a few years.