One possible solution is to change the default address book in Skype for Business. Here are the steps:
- Open Skype for Business and click on the gear icon in the top right corner.
- Select "Tools" and then "Options".
- Click on "Contacts" and then select "Address Book".
- Choose "Global Address List" from the drop-down menu and click "OK".
If this doesn't work, you may need to check your Outlook settings to ensure that the Global Address List is set as the default address book there as well.