CollectionView ScrollTo not working properly with dynamic size children (e.g. Expanders)

[gchapeaux]

Description

This bug report was opened following this question on StackOverflow.

I have a CollectionView bound to a Collection of objects. The ItemTemplate of this CollectinView consists in a single Expander. I want to implement the following behavior :

• By default all the Expanders are not expanded
• When clicking an Expander header, it opens it, closes every other expanded ones, and then scrolls to the expander so it ends up at the top of the list (or as high as possible if there is not enough objects below)

However it doesn't work quite as expected, as I am meeting two issues :

• When scrolling to an expander, the view doesn't always end up at the correct position, and it seems to scroll too far down (for example, when clicking the 1st expander of the list, then the 2nd)
• It seems something is causing the expanding of a second expander when expanding an expander and there are enough items in the Collection (in my Minimal reproducible example, when expanding the n-th expander it expands the n+15-th as well).

Steps to Reproduce

No response

Link to public reproduction project repository

https://github.com/gchapeaux/MRE_ExpanderCV/

Version with bug

9.0.10 SR1

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

Android

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

[Zhanglirong-Winnie]

This issue has been verified Visual Studio 17.13 Preview 2.1 (9.0.30 & 9.0.10 & 9.0.0). Can repro this issue on Android platform.