"Fatal error: No ObservableObject of type ResponderChain found. A View.environmentObject(_:) for ResponderChain may be missing as an ancestor of this view."

[Amzd]

This happens when you don't forward the EnvironmentObject.

If you have a sheet or a ViewRepresentable layer you have to manually forward the ResponderChain.

.sheet(isPresented: $showSheetView) {
    ExampleModal().environmentObject(chain)
}

More detailed explanation of why you have to do this:
https://medium.com/swlh/swiftui-and-the-missing-environment-object-1a4bf8913ba7

Long story short, it seems that when we present a new View or Action Sheet that entity is no longer considered to be in the current view hierarchy.

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Note: If you have issues with the modal being initialized when the ResponderChain changes then switch to .withResponderChainForCurrentWindow()