Auto Update Stats not updating Statistics
The new calculation is only used if trace flag 2371 is enabled, except on SQL Server 2016 when the context database compatibility level is set to 130, where it is the default behaviour. See Microsoft KB 2754171:

Controlling Autostat (AUTO_UPDATE_STATISTICS) behavior in SQL Server

Statistics are not updated when data is modified. A statistics update is triggered when cost-based optimization finds that interesting statistics for the query are stale.

The optimizer does not enter cost-based optimization for very simple ("trivial") queries, where a single obvious plan is always optimal. No statistics updates occur in that scenario.

See the Microsoft White Paper Plan Caching and Recompilation in SQL Server 2012 by Greg Low.