Hello @RobinS226 ,
Are you exporting a file of contacts and then uploading the file into your account or are you using a plugin from the marketplace to upload contacts? Are you getting an error when trying to add contacts?
If you can reply with the answers to these questions, and any other information that you have it will help us to better assist you.
Thanks for letting us know that it is worked out @RobinS226 ! Were there any steps that you had to perform to get it working again that you might be able to share in the Community?