Default [Q]Cannot see any files in internal memory after flashing stock

I tried to reflash stock KRT16S from CM 11 M1 in order to update to KOT49E (CM11 can have higher benchmark scores but apps loading is actually slower). But after flashing KRT16S, now I can find any file in internal memory, whether from file browser on Android or in Windows. Anyone knows how to fix it?
edit: well, I realize that flashing stock will wipe all data, so nothin more to say.