Thank for getting back to me htwydell,

I'm pleased you were able to speak to a member of our team about this. Yes the correct way to rollback in Advanced would be to unlock and then delete the pay run itself, and re-run this to allow any changes made within the settings to take effect. 

Have you tried clearing the cache on the browser or signing in via an incognito window since re-assigning the employees to see if there is a cache issue causing this message?

Thanks again :)