CSV import forms list read-only custom fields

[jeremystretch]

NetBox version

v3.3.4

Python version

3.8

Steps to Reproduce

1. Create a read-only custom field for the site model
2. View the site CSV import form

Expected Behavior

The read-only custom field should not appear in the list of available fields.

Observed Behavior

The field is included in the reference list, although it is not recognized as a valid field when submitting data.