If in the same situation you try the default EuroScope tag function to open the COPN altitude popup and it doesn't open, then its a EuroScope bug for sure. But if that works and the corresponding plugin function doesn't, then it can be either one - the plugin's fault for not requesting the popup to open when it should, or EuroScope's fault for not opening the popup when requested. There's no way for you to know where it goes south between clicking the mouse button to start the plugin's tag function and the popup not opening as expected.
