Display field missing from serialized rack unit in REST API

[jeremystretch]

NetBox version

v2.11.9

Python version

3.7

Steps to Reproduce

1. Create a rack with 10 units
2. Note the ID of the created rack
3. Make a REST API request for the rack's elevation (in JSON format, not SVG):

GET /api/dcim/racks/<ID>/elevation/

Expected Behavior

The serialized representation of each rack unit should include a display field.

Observed Behavior

The display field is not present.