This could have one or more of the following reasons:
1. Your privacy settings
Your new contacts will only be shown to your network if you allow that in the following privacy settings:
- Click on your profile image in the top right corner of the XING website.
- Click on Settings.
- Click on Privacy.
- Click on Network news updates.
- Activate the option My new contacts.
2. You have more than 250 contacts
Once a XING member has more than 250 contacts in their network, not all their contacts will be featured on the homepage anymore. Unless the new contact has less than 50 contacts themselves. The reason for this is that otherwise the news feed would be full of contact confirmations and other information would be drowned out.
By the way: You can see the last 10 contacts you added including the date the contact was confirmed by clicking on "Your network" in the left sidebar and then on "Latest contacts".