Indexed view not being used - SQL Server
This happens often if the optimiser thinks it can do better with the base tables.

If I create an indexed view, I tend to always use NOEXPAND to make it use it. I also compare the query statistics to ensure that it adds some benefit. That is, if I identify a useful indexed view I want the optimiser to always use it.

Example:

SET STATISTICS IO ON;
SET STATISTICS PROFILE ON;
SET STATISTICS TIME ON;
SELECT * FROM MySchema.myIndexedView ACB WITH (NOEXPAND) WHERE ...;
SELECT * FROM MySchema.myIndexedView ACB WHERE ...;


Note that depending on version, you may suffer from predicate pushing issues.

Note that this answer is generic because we don't have code and queries to look at