iOS 26.5.1
I got my related immortals (Trogolodin and Empyrion) to the required level (27+) to finish upgrading the weapon, which would allow me to meet the task requirement. The task is still presenting as though the weapons haven’t been fully upgraded, even though they are in the collection. I’ve tried closing and reopening app and reinstalling.
Have you opened any keys post hitting the requirement? Other people with kingdom tasks not showing as complete have got them to complete by doing this. No guarantee but maybe worth a try.
I noticed that pattern as well and yeah, I opened some gold and glory chests. It wasn’t keys though, just the respective resource. I also opened chests with shiny keys and dust. None of these worked. Then I opened some event chests with 50 event keys, and that worked for some (the 3rd task in Nexus and Grosh-nak, and the first task in Vulpacea), but not the weapon tasks that my bug report relate to (Zaejin and Nexus Task 2).