Google Messenger: Incorrect profile letter

I recently moved from Hangouts to Messenger as my default SMS app. The profile letter icon against the messages I send is showing to be incorrect (letter 'S' instead of 'R' which shows up on other Google apps that I use). I have since changed my Google profile picture but even that does not show up, 'S' persists. I am not sure if this is a bug or if my account has been compromised. Any help to figure this out?