Broken inkCanvas in WinUI 2.6

[Nazgul37]

I'm using an inkCanvas in my UWP app, but many users have been unable to draw in it with their stylus.

Apparently this is a bug due to the rounded corners affecting WinUI 2.6, as was discussed in the previous Microsoft QA Forum where I was trying to get help, linked to here: [https://docs.microsoft.com/answers/questions/523623/uwp-inkcanvas-works-only-on-some-devices-but-not-o.html]()

Steps to reproduce the behavior:

1. In my app, 'enScore' from the Windows 10 store, download the app and open it.
2. Click import PDF in the top right, then click the PDF File to view it, once added to your library.
3. Try to draw with a stylus over the PDF, in enScore. It won't ink. This is the issue, with the inkcanvas overlayed on the PDF.

Expected behavior

In step 3 above, drawing with a stylus should leave ink and annotations.

Environment

NuGet Package(s): 

Package Version(s): WinUI 2.6

Project .NET Version:
- [ ] .NET Framework (version: )
- [ ] .NET Core 3
- [ ] .NET Core 3.1 Preview (version: )

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] Insider Build (build number: )

App min and target version:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] Insider Build (xxxxx)

Device form factor:
- [x ] Desktop
- [ ] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio 
- [ ] 2017 (version: )
- [ ] 2019 (version: ) 
- [ ] 2019 Preview (version: )

Additional context

Has been previously discussed at the Windows QA link above, and was referred to create this GitHub Issue after the problem was confirmed by Microsoft Engineers.

[ghost]

Hello Nazgul37, thank you for opening an issue with us!

I have automatically added a "needs triage" label to help get things started. Our team will analyze and investigate the issue, and escalate it to the relevant team if possible. Other community members may also look into the issue and provide feedback 🙌

[michael-hawker]

InkCanvas is part of WinUI, seems like there's issues already open here https://github.com/microsoft/microsoft-ui-xaml/issues/6021 for something similar. Please add to the threads on the WinUI repo. Thanks!