My numeric and decimal custom ticket fields are missing in reporting.
The data for these field types will populate under Metrics within a query. These custom ticket field types store numeric values that are calculated similarly to system metrics.
For the full list of custom field types and their object type in Explore, see this article: Reporting with custom fields.
Alternatively, you can follow this recipe to convert these field types into attributes, here: Explore recipe: Converting between metrics and attributes.