Why is my phone not reporting free space properly?

[AC Question]

I'm running Android 6 on a 3rd generation Moto G. Internal storage reports that I'm using almost 4GB of space, however, when it breaks it down by type, altogether it all adds up to less than 2.5GB.

How do I find out where the discrepancy lies here?

 

[anon(9983233)]

Have you actually explored the system usage/monitoring settings and noticed where all the data is being used?.. then have you actually reset these settings or cleared the cache folder associated with these apps etc?.

 

[Parrot0123]

I don't see any options in the settings called "System Usage/Monitoring". Where would I find that?