It seems myself and multiple other developers have encountered this problem when scripting Dialogs. The DialogChoiceSelected event for Dialogs does not work in server scripts with Filtering Enabled on. It’s not a surprise to me now that I have figured it out (when I finally did). Now that all games are FE, this is important. The articles about this have no mention of this event being only client side. The example code provided kinda implies that the dialog and script are in the workspace, where local scripts won’t run. Below I will link the articles.
https://www.robloxdev.com/articles/Shop-Dialogs
https://www.robloxdev.com/articles/Usage-of-dialogs
In short: Add notation that .DialogChoiceSelected is client-side only.