Embedded List does not show the Display Value of Reference Field. Instead it shows the sys_id (SysID).
The field is a reference field, but instead of the display value being showing sys_id.
Any ServiceNow Release
Dictionary record of the custom field is set as Display =true. When compared with out of the box table, the it was the “Number” field which has set as Display = true.
In order to see value on embedded lists make Number as Display =true.
- Nested reference fields used as display values display as sys_ids when used as the sort field in a list