• More info:
  This is not regression issue, also can reproduce on .NET Framework & .NET Core 3.1 & NET Core 5.0.

• .NET Core Version:
  .NET SDK 6.0.100-alpha.1.20513.14

• Have you experienced this same bug with .NET Framework?:
  Yes

Problem description:
An error appeared for DateTimePicker control that 'An element of the given ControlType must support the ExpandCollapse pattern'.

Minimal repro:

1. Create a winforms core project with a DateTimePicker control.
2. Build and run the core project.
3. Observe DateTimePicker using the Accessibility Insight & Inspect tools .

Or

1. Open the attached project.
   CoreProjectIssue.zip
2. Build and run it.
3. Observe the DateTimePicker using Accessibility Insight & Inspect tools.

Actual behavior:
In the Accessibility Insight tool, an error 'An element of the given ControlType must support the ExpandCollapse pattern' appeared.
In the inspect tool, the 'IsExpandCollapsePattermAvaliable' property value is false.

Expected behavior:
No error appeared.