ItemsRepeater can't scroll manually using ChangeView when used in ScrollViewer

[hupo376787]

Describe the bug
Hi, I'm using ItemsRepeater, and surrounded in a ScrollViewer. I have disabled ScrollViewer's HorizontalScrollMode and VerticalScrollMode. And I want to use ChangeView method to scroll.
But it doesn't works.
However, ScrollToHorizontalOffset/ScrollToVerticalOffset works.

Steps to reproduce the bug

Steps to reproduce the behavior:

<Grid>
                    <muxc:ItemsRepeaterScrollHost Margin="12" Loaded="ItemsRepeaterScrollHost_Loaded">
                        <ScrollViewer
                            x:Name="sss"
                            VerticalScrollBarVisibility="Hidden"
                            HorizontalScrollBarVisibility="Hidden"
                            VerticalScrollMode="Disabled"
                            HorizontalScrollMode="Disabled">
                            <muxc:ItemsRepeater
                                x:Name="HorizontalRepeater"
                                ItemsSource="{x:Bind product}"
                                ItemTemplate="{StaticResource HorizontalTemplate}">
                                <muxc:ItemsRepeater.Layout>
                                    <muxc:StackLayout Orientation="Horizontal" Spacing="12"/>
                                </muxc:ItemsRepeater.Layout>
                            </muxc:ItemsRepeater>
                        </ScrollViewer>
                    </muxc:ItemsRepeaterScrollHost>
                    <Button
                        x:Name="ButtonLeft"
                        Tapped="ButtonLeft_Tapped">
                        <FontIcon FontFamily="Segoe MDL2 Assets" Glyph="&#xE76B;" FontSize="18" />
                    </Button>

                    <Button x:Name="ButtonRight"
                        Tapped="ButtonRight_Tapped">
                        <FontIcon FontFamily="Segoe MDL2 Assets" Glyph="&#xE76C;" FontSize="18" />
                    </Button>
                </Grid>

Then use this code to scroll.
sss.ChangeView(sss.ActualWidth, null, null); This code does't not work.

But sss.ScrollToHorizontalOffset(sss.ActualWidth); works.

Expected behavior

ItemsRepeater can scroll left/right using ChangeView method.

Screenshots

Version Info

OS: 18362.418

And a weird thing is, I actually saw this bug on 18362. But last night I upgrade my pc to 1909(18363.476), ChangeView method works.

NuGet package version:

Microsoft.UI.Xaml: 2.2.190917002

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
May 2019 Update (18362)	Yes
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Mobile
Xbox
Surface Hub
IoT

Additional context

In 18362(1903) or lower, ScrollToHorizontalOffset/ScrollToVerticalOffset works.
In 18363(1909), ChangeView and ScrollToHorizontalOffset/ScrollToVerticalOffset works.

So for a better compatible， ScrollToHorizontalOffset/ScrollToVerticalOffset is the best choice, although this api is out of date.

[jevansaks]

@ranjeshj is the problem that downlevel the customer needs the ItemsRepeaterScrollHost?

[jevansaks]

Oops I see it in the repro. Ok, @ranjeshj can you investigate?

[ranjeshj]

@RBrid - Is this expected behavior with ScrollViewer ? I know that setting some properties on ScrollViewer stop it from scrolling through interaction but i dont remember of the top of my head. Is that the same for using the APIs as well ?

[RBrid]

@ranjeshj, no - there is no way to turn off programmatic view changes, like for user interactions.

The first key questions to answer are:

• when the call is made, what are the values of
  sss.ActualWidth
  sss.ViewportWidth
  sss.ScrollableWidth
  ?
• what is the return value of ChangeView? True or False?
• is a finger down on the ScrollViewer when the call is made? (is the call triggered by a user gesture?)

Thanks.