[Bug] View not updated from Viewmodel when different page is open

[Raffro]

Description

I have a shell tabpage view. In one of the tabs (Page A) i have a devexpress collection view with datatemplate. The datatemplate contains mainly of two labels which are bound to a specific datatype with to string properties (full property, onpropertychanged is called when a value is assigned). One of them is fixed and one changes.

If the collectionView item is tapped, a new page (Page B) is openend (e.g. a new page with a checkbox list). On the basis on what is selected in this page (still the same viewmodel), the previous page (Page A) on the navigation stack shall be updated. To do this, the second string is changed when a checkbox is selected.

But when I return to the page with the collectionView (Page A), the label is not updated. I checked via Debugger and the property has changed. For some reasons the page, which is not on top of the stack does not update its bindings.

To verify that, I added a button on my collectionView page (Page A), which goes through all collectionViewItems and assigns an empt string and afterwards the updated value.

How can I force the page to update its contents (and still be conform to MVVM pattern)? The only way which is working right now is overriding the onappearing method and assigning to all items of the collectionView an empty string and right afterwards the previousy assinged value. Is there not another way?

[Raffro]

Okay, basically i have two sub-page types : a checkbox listview and a rangepicker view. the checkboxes have a custom viewmodel command which is executed on the Checked event. The rangepicker (numeric edits from devexpress) have their own "ValueChangedCommand" which calls the viewmodel command via {Binding BindingContext.UpdateDisplayParameterCommand, Source={x:Reference ParentPage} }

It just doesnt update the first page from the numeric edit, although the onpropertyChanged method is called properly