Query Store Force Plan feature doesn't work

Query Store Force plan feature doesn't appear to be enforcing the plan.

I'm aware of Query Store - Forced Doesn’t Always Mean Forced; however, my plan may not change insignificantly, but query optimizer may continue to choose incorrect indexes, loop choices etc.

Basically: it doesn't honor my forced plan choice. I've forced many plans and It Just Doesn't Work.

1. There are 0 failure counts or reasons when I look at sys.query_store_planforce_failure_count.
2. Extended event query_store_plan_forcing_failed doesn't yield anything. 0 Events.

For example, a plan which was forced on 20.09. Only 1 compilation happened to use forced plan.

The plans differ wildly, one using Hash Match join with INDEX 1, the other using Loop Join with INDEX 2.

Version: Microsoft SQL Server 2016 (SP1-GDR) (KB3210089) - 13.0.4202.2 (X64)

What am I missing here?