RibbonContextualTabGroup not shown

[znakeeye]

Place your issue description here.
Upgraded from v3.6 and now my RibbonContextualTabGroup is not shown even though I explicitly set Visibility="Visible". Its children, two RibbonTabItem elements, are indeed shown. Using Snoop, when selecting any of these two tab items, the contextual tab group suddenly appears!

In my code, the child items become visible when setting a certain flag:

<fluent:Ribbon.ContextualGroups>
  <fluent:RibbonContextualTabGroup x:Name="MyContextualGroup" Header="My Tools"
                                   Visibility="Visible"
                                   BorderBrush="Green"
                                   Background="Green"
                                   Foreground="DarkGreen"
                                   FontSize="10" />
</fluent:Ribbon.ContextualGroups>
<!-- ... -->
<fluent:RibbonTabItem Header="Foo" Group="{Binding ElementName=MyContextualGroup}"
                      Visibility="{Binding Path=IsFooBarVisible,Converter=...} />
<fluent:RibbonTabItem Header="Bar" Group="{Binding ElementName=MyContextualGroup}"
                      Visibility="{Binding Path=IsFooBarVisible,Converter=...} />

These is what I see. When IsFooBarVisible is set to true:

Then I select the Foo tab using Snoop. Suddenly it is refreshed...

Then I select the Bar tab using Snoop. Not sure what happened here. The tabs switched places:

And after some fiddling around, the tabs are finally refreshed. After this, the tabs look good even when toggling the visibility.

---

Environment

• Fluent.Ribbon v7.0.0-alpha0456
• Windows 10
• .NET Framework 4.5.2

[znakeeye]

I found a non-intuitive solution. Either I really encountered a bug, or we should make a note about the observed behavior.

Works:

<fluent:RibbonTabItem Group="{Binding Source={x:Reference MyContextualGroup},Mode=OneWay}" ... />

Not working:

<fluent:RibbonTabItem Group="{Binding Element=MyContextualGroup},Mode=OneWay}" ... />

[batzen]

Will have a look at this.
Had to switch from x:Reference to Element in the showcase application because .net core 3.0 doesn't currently support x:Reference