This happens just for UWP and WPF (so far).
See the samples cards
I can't see the sample cards


Change the CollectionView to ListView.
as for UWP you have to resize the app (as workaround)
as for WPF. it is XF issue. We use ControlTemplate and CollectionView which are not implemented in XF for WPF
as for GTK. similar to WPF. But I also updated PancakeView in my PR, which fixes build issue
https://github.com/xamarin/Xamarin.Forms/pull/11394 might fix this issue when merged...for uwp
So for now the workaround will be to not use ContentTemplates for the list pages.
XF 5.0.1 should fix it for WPF: https://github.com/xamarin/Xamarin.Forms/pull/7728
@VladislavAntonyuk, maybe this can take more time, it's a too old PR and is targeting the wrong branch there.
@pictos I am not sure, but I think you are a bit closer to the Xamarin Forms owners. It would be nice if you ping them to review the PR. Because mostly developers create apps for Android and iOS, it is less risky to break something by fixing this PR for WPF.
@VladislavAntonyuk sure, I'll ping them later today.
Most helpful comment
https://github.com/xamarin/Xamarin.Forms/pull/11394 might fix this issue when merged...for uwp