Custom control fails to update other control

To illustrate the problem I created a custom control PingPongView with the following behavior:

Custom control fails to update other control

To illustrate the problem I created a custom control PingPongView with the following behavior:

Custom control fails to update other control

To illustrate the problem I created a custom control PingPongView with the following behavior:

Unhandles Exception with Databinding

why is this:

Maui how to bind commands in CollectionView items

How can I set any command in CollectionView to a command in the view model?