BackButtonBehavior not bound

[michele-guion]

Description

I have a ContentPage, in which I define BackButtonBehavior as follows:

<Shell.BackButtonBehavior>
    <BackButtonBehavior Command="{Binding BackCommand}">
        <BackButtonBehavior.IconOverride>
            <FontImageSource Glyph="{x:Static enums:IconFont.Close}"
                             FontFamily="MaterialDesignIcons"/>
        </BackButtonBehavior.IconOverride>
    </BackButtonBehavior>
</Shell.BackButtonBehavior>

Since .NET9, the icon override stopped working and that's a known bug #32050.
I switched to .NET10 and also the command stopped working.

### Steps to Reproduce

_No response_

### Link to public reproduction project repository

_No response_

### Version with bug

10.0.11

### Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

### Last version that worked well

9.0.120 SR12

### Affected platforms

Android

### Affected platform versions

_No response_

### Did you find any workaround?

This is a binding error, for which I use this workaround in the page constructor:

Shell.SetBackButtonBehavior(this, new BackButtonBehavior
{
Command = viewModel.BackCommand
});

Relevant log output

[michele-guion]

Setting IconOverride in the workaround code does not solve the issue. So these are two distinct issues.

[kubaflo]

Hi! Could you please attach a repro. I can't replicate it

[kubaflo]

The IconOverride has been fixed here #32080

[michele-guion]

In a new sample project, it seems to work. I'm currently investigating why it stopped working in our project.

[michele-guion]

I managed to replicate the case. In our app, we dynamically add controls to the sub page. The controls are bound to a model.
In the ZIP file I attached you can find a small project which replicates the case.
The app has a MainPage with a Button that opens a SubPage, whose content is dynamically filled with instances of SubPageControl, each bound to SubPageControlModel.
The SubPage is bound to SubPageModel, which contains a RelayCommand called Back, bounf to BackButtonBehavior.
If you leave the app as it is, the command is not called. Instead, if you comment the assignment to BindingContext in SubPageControlModel class, the command is called.
I hope it's enough.

BackButtonIssue.zip