Rack Reservations - Custom Field REST API filtering not working

[anttof]

Environment

• Python version: 3.7.9
• NetBox version: 2.10.4

Steps to Reproduce

1. Create Custom Field (tried text, boolean, integer so far) - Apply field on rack-reservations.
2. Create rack-reservation and fill in created custom-field.
3. Use "?cf_customfieldname=value" REST API filter to filter rack-reservations
4. Example:

• https://netbox.net/api/dcim/rack-reservations/?cf_service_id=123456 <-- Displays all rack-reservations, including those with other cf "service_id" than "123456"
• https://netbox.net/api/dcim/devices/?cf_service_id=123456 <-- Works correctly and displays only devices with cf "service_id" set to "123456"

Expected Behavior

Only rack-reservations matching custom-field rest api filter should be matched and displayed.

Observed Behavior

All rack-reservations are displayed with the rest api filter applied. Including those not matching the filter.