This is the only solution that worked for me, and the reason some people don't have this problem is that the only files you can't access (after selecting transfer files) are on the external memory.
Just a little extra detail...it is necessary to clear the cache of two different apps - "External Storage" and "Media Storage". To do this, you have to select System->Apps, then tap the three vertical dots in the upper right hand corner, then tap "Show System" and now the Android system apps are shown along with all your other apps. For both apps ( "External Storage" and "Media Storage".) tap "Storage" (not a button, just a text field), then you will see the buttons to "Clear Data" and "Clear Cache". Do both and reset the phone. It will take a few minutes for all the files to appear, as the phone caches the configuration.