FIXED! OK Apple Watchers! I have been right there with you experiencing staggering battery drain on my Ultra 2 since the Watch OS 10.4 update. My wife has the exact same watch with very similar setup. We updated both watches at the same time. Her watch did not experience any battery drain issues. Who knows why some of us took such a huge performance hit after this update while others did not? Considering the vast resources at their disposal, Apple can and should do a better job than this of scrutinizing all updates before release. While community beta testing feedback is certainly valuable, if it is being relied on too heavily, Apple has got to dedicate more resources to taking ownership of every update and every issue it might introduce to us. Enough about that already! Now for the fix! A couple of posts have mentioned a hard reset fix for this issue. I am extremely relieved to report that it works if done correctly!! First off, make certain that you know how to perform a hard reset on your watch and your iPhone. You have to do both! (Normal power off and on have no effect on this issue. Nor did any number of battery consumption reducing settings changes)
On the Ultra 2 watch a hard reset requires pressing the digital crown and the side button simultaneously and holding until the Apple logo appears. On newer iPhones, quickly press and release volume up then volume down and then press and hold the side button until Apple logo appears. I hard reset the phone first and then hard reset the watch while the phone was starting up. I wanted the phone to be up and running when the watch finished resetting and started searching for the phone. I hard reset both twice back to back. Maybe once would have done it but I am just reporting exactly what I did to get my watch back. I cannot express how frustrated and angry I have been (not without getting my post removed that is) about the battery performance loss on my Apple Watch Ultra 2 after updating to Watch OS 10.4 The watch is the most prized gadget I have ever owned and ever since I purchased it I have been overwhelmed by the technology and innovation that went into it’s design. That is why the hit I took after the update pushed me over the edge. That and the fact that I know Apple can do better. There needs to be a reckoning, perhaps a complete overhaul of the entire update development process. Please Apple: Don’t do this to me again.