You all figured this out yeah? Been a few years since this thread was addressed… but I accidentally hit “Resave All” and then wanted to know exactly what the engine was doing so I googled and found this thread.
I’ve been working in UE4 4.21 and now they have it so that you can just right-click the Content folder in the Content Browser and simply click Resave All. Sounds like it’s saved a lot of headaches!