It's not just sideloaded apps. Apps for the Gear from the Samsung App Store have disappeared too after this new Gear Manager update. What's weird is that they show as still being installed in Gear Manager -- and in the Samsung App Store -- even though they're not on the Gear. I don't know of any way to force Gear Manager to make sure they're installed on the Gear, so I guess I'll have to delete them from my phone and reinstall them. Idiots.