The candidate can't receive any messages because their preferred communication channel doesn't exist

Summary:

Hello - we just received our 23D release and we are noticing the following message is appearing on some candidates:

"The candidate can't receive any messages because their preferred communication channel doesn't exist."

Did something change in 23D making this appear?

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

23D

Code Snippet (add any code snippets that support your topic, if applicable):