I was having exactly the same problem after updating to the latest osTicket version and LDAP plugin and I found where the problem was.
In the file: ajax.users.php, inside the function
function addRemoteUser($bk, $id) {
$bk was "ldap" instead of "ldap.p33i11" (in my case)
If I just add $bk="ldap.p33i11"; it works fine.
I don't know where it gets the "ldap" from, all the users and staff have the correct .p33i11 (in my case). I even created a database dump to look for "ldap" or 'ldap' and I didn't find any results.
I would like to solve it in a proper way. It only happens with remote users.
Edit:
I think here is where the problem starts, inside the file authentication.php of the auth-ldap plugin:
class StaffLDAPAuthentication extends StaffAuthenticationBackend
implements AuthDirectorySearch {
static $name = /* trans */ "Active Directory or LDAP";
static $id = "ldap"; <------------------------
Edit2:
I know where the strange .p33i11 comes from, is .p<plugin_id>i<instance_id>
I think the main problem is the auth-ldap plugin hasn't been updated to support plugin instances. ;-)