Custom Record Online Form > Select Fields > No option to select Section

When creating Online Form for a Custom Record, under Select Fields, there is no option for Section to choose.

Steps to reproduce:
1. Navigate to Customization > Lists, Records, & Fields > Record Types.
2. Edit the Custom Record.
3. Go to Online Forms > click on New Online Form.
4. Enter Title.
5. Under Select Fields, enter a Field.
6. Go to Section column.

Actual Results:

No option to select to assign Section for the field.

To resolve the problem, create a Subtab first for the Custom Record.

Steps to Reproduce:
1. Navigate to Customization > Lists, Records, & Fields > Record Types.
2. Edit the Custom Record.
3. Under Subtabs, enter a Title.
4. Click Save.
5. In the Online Forms tab > click on New Online Form.
6. Enter Title.
7. Under Select Fields, enter a Field.
8. In the Section column notice the Subtab will now appear under Section.

Note:
1. Under Set Up Appearance tab in the Online Form, users can enable the Unlayered Sections in order to display the untabbed section. If you set the Unlayered Sections disabled, the Section will appear as tabs in the Online Form.