Collection fields not pulling actual locked fields

[rg9400]

Describe the issue
When running .fields on a collection object, you get an empty list back ([]) each time, even if that collection does indeed have locked fields. Both the database and the XML display locked fields, so the bug seems to be isolated to plexapi

EDIT: I am using the latest commit version of plexapi from the master branch. When I downgraded to the last release (4.1.2), everything worked as intended.

Code snipppets
The below are different ways of pulling data for the same exact collection

From the Plex XML

<Field locked="1" name="summary"/>
<Field locked="1" name="thumb"/>
<Field locked="1" name="art"/>

From the DB

lockedFields=7|9|10

From the Plex Web UI

From Python-PlexAPI

>>> collections = plex.library.section("Movies").collection()
>>> collection = collections[0]
>>> collection.fields
[]

Expected behavior
.fields should give a list of fields that are locked for collection objects, like it does for other objects.

Enviroment (please complete the following information):

• OS: plexapi on Windows 10, Plex in Docker
• Plex version: 1.20.3.3437
• Python Version: 3.9.0
• PlexAPI version: 4.1.2 (commit 8ec0c4c)

[JonnyWong16]

Bug caused by removal of Field from the list of PLEXOBJECTS.

3746b4e