This is a common issue when the ListView component is inside StackLayout and the ItemSource property is initially an empty list (or empty ObservableCollection), the ListView is not visible on screen, even after items are added later on.
I have logged this in our Feedback Portal, you could follow the item in the link below:
At the moment, suitable workaround I could suggest is replacing the StackLayout with Grid layout.
For more details, please take a look at the topic in our Forum about ListView not showing up here
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