Text-bound Runs inside of a TextBlock are invisible (not rendered) half the time when their Text changes

[fitdev]

Describe the bug

<TextBlock TextWrapping="Wrap" />
        <Run Text="{Binding Profile.FirstName}" />
        <Run Text="{Binding Description}" />
</TextBlock>

Given the XAML above, whenever either Profile or Description change, roughly half of the time the Runs become invisible (even though their IsVisible is true, and their Bounds are correct).

Everything works properly if instead TextBlock's Text itself gets updated via binding.

To Reproduce

From a viewmodel, repeatedly change the TextBlock-nested Runs' bound properties.

Expected behavior

The Runs should remain visible, i.e. rendered all the time.

Avalonia version

11.1 RC1

OS

Windows

Additional context

DotNet 8

[timunie]

please attach a full minimal sample