It looks like a project structure that Copilot cannot handle, indeed. Copilot uses Vaadin IDEA plugin to detect and resolve modules in the project when available. Otherwise, Copilot assumes the project structure as single module, and resolving it from the available data within the application context
Could you share more details about your environment?
Do you happen to have Vaadin IDEA plugin installed? - Based on the breakpoint in screenshot, you have the plugin. Could you share the version of the Plugin?
Are there any log messages that Copilot printed?