ID 438224 - PySide2 - Adding an item to a QComboBox, after it has been created, cuts off the text in the in the sub-widget

Problem summary
Adding an item to a QComboBox, after it has been created, cuts off the text in the in the sub-widget (pop-up menu).

Customer reported version
Nuke 12.1v2

Customer reported platform
windows10

Steps to reproduce

1) Open Nuke.

2) Run the following code in the Script Editor:

from PySide2 import QtWidgetsclass TestAddingToComboBox(QtWidgets.QDialog):    def __init__(self, parent=None):        super(TestAddingToComboBox, self).__init__()        mainLayout = QtWidgets.QVBoxLayout()        self.com = QtWidgets.QComboBox()        mainLayout.addWidget(self.com)        self.btn = QtWidgets.QPushButton("Add")        self.btn.clicked.connect(self.thing)        mainLayout.addWidget(self.btn)        ### Pre-added For comparison        self.com2 = QtWidgets.QComboBox()        self.com2.addItem("aaa_bbb_ccc")        self.com2.addItem("aaa_bbb_ccc_ddd_fff_ggg")        mainLayout.addWidget(self.com2)        self.setLayout(mainLayout)    def thing(self):        self.com.addItem("aaa_bbb_ccc")        self.com.addItem("aaa_bbb_ccc_ddd_fff_ggg_hhh")mainWindow = TestAddingToComboBox()mainWindow.show()

3) In the Window that appears, press the Add button. This will populate the top dropdown menu with a couple of items.

4) Click the top dropdown menu and notice that the longest item/text is cut off at the end:

The bottom dropdown menu is included to show a pre-populated QComboBox that works as expected.

Expected behaviour
Adding an item to a QComboBox, after it has been created, should not cut the text off at the end.

Actual behaviour
Adding an item to a QComboBox, after it has been created, cuts off the text in the in the sub-widget (pop-up menu).

Workaround
Adding the following line (in bold) to the script may resolve the issue:

        self.com = QtWidgets.QComboBox()
        self.com.setSizeAdjustPolicy(QtWidgets.QComboBox.SizeAdjustPolicy.AdjustToContents)
        mainLayout.addWidget(self.com)

Reproduced by support
This bug has been reproduced in:
Nuke 12.1v3 - Windows 10 - Linux CentOS 7 - macOS 10.13 (High Sierra)

Nuke 12.1v1 - Windows 10 - Linux CentOS 7 - macOS 10.13 (High Sierra) - Regression 

Unable to reproduce bug in:
Nuke 12.0v6 - Windows 10 - Linux CentOS 7 - macOS 10.13 (High Sierra)

Earliest version tested
Nuke 12.0v6
- This issue doesn't appear in this version and has regressed