Hello Shyntil,
Could you go ahead and double check for me, please, if you indeed have all the Dex Data needed for this quest? As shown in the Requirements of the Legendary Megathread, you'll need the following Seen Data of these Legendaries in particular:
Apologies if this may seem tedious to you, but as our Content Scripters are quite busy, we want to ensure that all other possibilities—such as a misunderstanding of the quest requirements—are completely ruled out. If you indeed have all the necessary requirements fulfilled, we will need the help of a Content Scripter to resolve this issue.
Looking forward to your answer; until then, have a great day!
Kind Regards, Astraea.
number 240 - magby?