Why is my automation trying to assign to a user that doesn't exist?

[Danno]

I'm using Cloud Premium and have an automation that is failing. I want it to assign to a user in a role and it is failing with this message:

Error assigning issues

PRS-1978: (User 'rk:1bbb7c4d-929b-4b89-b108-a912d6937601' cannot be assigned issues. (assignee))

I do not understand why the user code is formatted this way although it looks like a user code I have from an outside email domain. I also cannot decipher who this user would be. I don't know what portion of the code to use.

Can someone explain how to solve this issue?

[JamieA]

When you say "number of codes" - what do you mean - the issue key?

[JamieA]

Will try to reproduce... but looks quite involved.