Teams Notification bot - Unable to fetch all the members using the bot.notification.installations()

Question

I have a notification bot which sends Custom adaptive cards to user on the basis of emails. The app is personal app and not a teams/group app. the notificaion is going out for some customer in a oganzation. and for some organizationn its not going out at all, it gives 'conversation not found error'. so my guess was that the user has not installed the app. but i did check with the customer and the app was installed

this is how i find member using the email and send it to the user

const member = await bot.notification.findMember(
      async (m) => m.account.email === receiverEmail
    );

for testing purpose, what i did i tried to console log all the members which have installed the app by using the below code

   // list all installation targets
    for (const target of await bot.notification.installations()) {
      console.log("\n\ninside installations")
      // "Person" means this bot is installed as Personal app
      try {
        const members = await target.members();
        for (const member of members) {
          console.log(member)
        }
        }catch (error) {

       throw new Error("error : " + error);
      }
    }

but for some reason, this is printing only 3 objects. not sure what is the issue here.