I have a simple list with one field I named ‘Recipient’. It is a name field that allows you to select other sharepoint users. The workflow has one action, send email that does a workflow lookup at the Recipient filed on the current item and returns the field as a semicolon delimited email address. When I create a new item and select myself as the recipient the email gets sent but if I select anyone else the workflow goes into suspend status with the following status:
Hi Mike,
please check user profile of that particular user exist or not. If not try full user profile synch.
Still if your not able to get, use fiddler to verify that.Usually , workflow picks from the UserInformationList which is hidden list using REST API’s. Once userprofile is exists automatically your few of profile properties will fall in UserInformationList.
please let me know, still if you face any issues.