Discord JDA can't get getMutualGuilds() to work

Question

Im trying to make a bot that sends a pm when someone joins a server, and then assigns a role based on reply to said Pm.

This is the following code i have so far for onMessageRecieved, issue is that user.getMutualGuilds() returns an empty list even though they are part of the same server as the bot.

    @Override
    public void onMessageReceived(MessageReceivedEvent event) {
 
        String DmRecieved = event.getMessage().getContentRaw();
 
        User user = event.getAuthor();
 
        boolean isBot = user.isBot();
 
        boolean startsWithAU = DmRecieved.toUpperCase().startsWith("AU", 0);
 
        boolean messageTooLong = DmRecieved.length() > 8;
 
        if (event.getMessage().getContentRaw().isEmpty()) return;
 
        if (isBot) return;
 
        if (!startsWithAU ||  messageTooLong) {
            user.openPrivateChannel().queue((chanel1 ->
                    chanel1.sendMessage("Not valid AU ID, please try again.").queue()));
        } else {
 
            List<Guild> guilds = user.getMutualGuilds();
 
            System.out.println(guilds);
 
 
        }
 
    }

Answer 1

I found the fix. The members needed to be cached in memory this was done by adding the following line to the JDA:

jda.setMemberCachePolicy(member -> true);