@Nimhain Managed to reproduce it regularly.
Steps to reproduce:
Select a name in chat
Fight their team
Open chat during the fight
Retreat, win or lose the fight
Still working on testing edge cases, and whether winning or losing also has the same effect. Will get back to you with those.
Edit: It still happens regardless of winning or losing.
This only seems to happen during the friendly Fight option. Doesn't happen in PVP or Explore.