What are pending, unknown and lost devices?

In your licensing reports, you'll sometimes see devices shown as 'pending', 'unknown' or 'lost' under your 'Uncounted devices' heading:

Pending devices are recently-added devices for which MobileIron hasn't yet calculated feature usage. MobileIron typically re-runs this report weekly, so you may need to wait a few days for these devices to be reflected in your licensing calculations.

Unknown devices are devices which MobileIron hasn't returned feature usage data for. This can happen when some data inside the MobileIron Core is in an inconsistent state, or where the device's unique identifier is malformed. 

Lost devices are devices which are still active on your MobileIron instance (i.e. they haven't been retired), but have been marked as 'lost'. They are therefore not allocated device feature usage and are not calculated for the purposes of license management. Note that this is different from a device being shown as 'out of contact' in IronWorks: a device can be out of contact (meaning it hasn't checked in for a period of time), but not marked as lost inside MobileIron. Typically 'lost' devices will also be out of contact, however.