There will be no overlay folder it's location is totally different and I don't think there possible could be any write error which file explorer u r using? It should be in internal storage. Like mine at bottomHa, nope. After re-applying theme, but not restarting, no .substratum folders or overlay folders show up anywhere. I am viewing hidden folders too. I think it is a write issue of some sort, but I can't exactly figure out what.