Object Name doesn't display within a Report on Report Types

This is a known limitation in Salesforce Reports. When the report type is a standard report type created automatically from a standard-to-custom object relationship, the specific object name is not exposed in the Report Type filter. The following workaround uses the 'Object Name' field as a secondary filter to narrow results to the correct custom object.

Workaround Steps:

A workaround for this situation is to configure the report filters as in the following example:

Example Workaround Configuration:

•  Report Type equals Opportunities with Custom Object
• AND Custom Entity: Object Name equals custom_object_api_name (use the Object Name from Setup, without the __c suffix, not the label).