LGA-YYZ is 12.5k not a great deal. JFK-YYC wouldn't load availability.
AA is never available and 12.5k DL is much less valuable then 12.5K AC/UA, plus no close in fees or YQ
Search seems very buggy.
Can't seem to do a nonstop search for any route unless it's also served by DL.
I searched YYZ-LGW for June nonstops only, as well as Canada-Hawaii nonstop, it showed results.
Give delta a day or two to sort it out, they have decent IT