Do I correctly understand that your code looks as follows:

PropertiesConfig.ts

export class PropertiesConfig {

}

index.ts

function f(p: PropertiesConfig){

}

If so, auto imports should operate correctly. Could you please create a new ticket on YouTrack and share your small example and the IDE logs(Help | Collect Logs and Diagnostic Data) there? We will research the issue and follow up with you.