hc:SplitButton DropDownElement.ConsistentWidth not work

[CodingOctocat]

Describe the bug

hc:SplitButton DropDownElement.ConsistentWidth not work

Steps to reproduce the bug

<hc:SplitButton HorizontalContentAlignment="Right"
                hc:DropDownElement.ConsistentWidth="True"
                Content="保存并应用"
                Style="{StaticResource SplitButtonPrimary}">
    <hc:SplitButton.DropDownContent>
        <hc:SimpleStackPanel>
            <MenuItem Header="保存" />
        </hc:SimpleStackPanel>
    </hc:SplitButton.DropDownContent>
</hc:SplitButton>

Expected behavior

No response

Screenshots

No response

NuGet package version

HandyControl 3.4.0

IDE

Visual Studio 2022

Framework type

.Net 6.0

Windows version

Windows 11 (22000)

Additional context

No response