I have discovered an issue with handling users logged in with oath.
My oauth log in has an ldap backend. The user details are defined by username, email, displayname.
It is the display name that is displayed in misago as the username. The display name can be "Firstname Lastname". Misago interprets this as "Firstname_Lastname".
If I go to try to initiate a private message with such a user the "start thread" button remains greyed out. I cannot add such a user to an existing private discussion. I also cannot successfully refer to such a user using @username. Yet the user exists in the site displayed as "Firstname_Lastname"