- Go to Inventory > Configuration > Warehouse Management > Locations
- In the list of locations, enable the column visibility 'Fill State'
- You can filter the locations per 'Empty', 'Filled', 'Being Filled' or 'Being Emptied' property.

- The Customers and Suppliers locations won't have their fill_state
  filled in with 'filled' for performances reasons as too
  much products quantities (aka quants) can exist in those locations.
- Some locations can be excluded too from the computation. Go to the 
  desired location and check the 'Exclude From Fill State Computation' box.
