Xamarin.forms: [UWP] ListView scroll issues

[davidbritch]

Description

I have a ListView that demonstrates using the new binding capabilities (TargetNullValue, Fallback Value). Unfortunately the ListView misbehaves on UWP. Following back navigation from the detail page, the list stops scrolling until fingers are replaced on screen.

This is only reproducible when running from a device with a touch screen. I first tested this by remoting from a device with a touch screen and I couldn't reproduce

Steps to Reproduce

1. Run the sample.
2. Navigate to detail page (click on a monkey).
3. Navigate back.
4. Scroll the ListView.

Expected Behavior

The ListView scrolls perfectly.

Actual Behavior

The ListView scrolls then stops, and only resumes when the scroll gesture is restarted (fingers removed and replaced).

Basic Information

• Version with issue: 3.2.0.729530-pre2
• Issue also exists with 3.1 haven't tested back any further
• IDE: VS2017 15.8
• Platform Target Frameworks:
  
  
  
  • UWP: 10.0.16299.0
  
  

Reproduction Link

DataBindingDemos.zip

[davidortinau]

When I run this I can scroll the list initially. When I navigate to a detail page (typically one later in the list) and navigate back, I can scroll until some databinding (I suspect) even triggers and then the list stops scrolling or responding to gestures. I can then lift my finger and resume scrolling fine.

I don't think you'll see my touches in this video, but you can see the list abruptly stop scrolling after navigating back to the list.

I confirmed this using 1 finger to scroll on my touch screen, and 2 fingers scroll gesture on the track pad. Same experience.

https://www.screencast.com/t/PB9d7j4iiT

[PureWeen]

I tested this on 3.1 and it's also an issue there so this doesn't appear to be a regression from 3.1 to 3.2