It works like the following:
Joomla user 1 has characters: Charater 1, and Charater 2
Character 1 and Character 2 cannot be on the same raid (as both controlled by a single person)
So if multiple characters are assigned to you, only one of them can be assigned to a raid, that’s normal.
There was a bug, which prevented multiple characters to be displayed, if no user was set, but that has been fixed in 0.7.1.
Please use Joomla built in updater and check it.