If you are hosted by Blackbaud:
Chat with Support and reference this article. 

If you are not hosted by Blackbaud:
  1. Restart your Connector. 
  2. In the Scheduler, initiate a sync or send your mapping metadata.

If the stop/start does not resolve, then complete the following on the server:
  1. On your desktop, go to Start > Run
  2. Type services.msc
  3. On this list, double click "Integration Service [your account id]"
  4. Click Stop
  5. In the Scheduler, initiate a sync or send your mapping metadata