[CX] Unresponsive Analytics service when using secondary indexes with numeric fields

When creating a secondary index with composite fields, and one or more of these fields have a numeric type (int, double), there is a chance that the Analytics will run into repeated ingestion failure when the following happens:
A document is updated such that the indexed numeric field value changes between a real value and null/missing.
As a workaround, make sure the indexed numeric fields always have values (i.e. not null or missing), or drop any composite fields indexes that have numeric fields.