Hi there. Please be sure to inspect the armor so you can see a more detailed explanation of the objectives. You're required to get kills in Strikes while using a subclass that matches the daily Solstice element. Don't mistake that for the singe when looking at the Strike modifiers — what you want to look at is the elemental buff on your character menu, Eva's daily bounties, or the element is says when selecting the EAZ activity. If you're sure you're using the correct subclass, try clearing your console's cache by shutting it down and unplugging it, then leaving it for around five minutes.