IBM MQ User Authentication for mixed case username

Question

I have and IBM Wesbsphere MQ installation on a Centos server. I have set up connection authentication that allows user of a group read_group to connect and view the queues. I have created a user developer and made it a member of the read_group. From a MQ Explorer running on a Windows workstation I am add and connect to the remote queue manager running on the Centos server.

I created a user called jane.doe and made it a member of the group read_group. I am able to connect using this user from MQ Explorer.

I created a user called John.Doe and made it a member of group read_group . I am not able to connect using this user from MQ Explorer.

For good measure I created a user called Ruth and made it a member of the group read_group. I am not able to connect using this user from MQ Explorer.

The exception thrown in MQ Explorer is

Access not permitted.You are not authorized to perform this operation. (AMQ4036)

The exception in the MQ error log is

AMQ9557: Queue Manager UserID initialization failed for 'Ruth'

EXPLANATION:
The call to initialize the User ID 'Ruth' failed with CompCode 2 and Reason 2035

ACTION:
Correct the error and try again.
----- cmqxrsrv.c : 2321 -----------------------------------------------

I have confirmed the group membership for all the above users is correct. I have confirmed I can log on to Centos without any issues.

It seems like the issue is the casing of the usernames.

The queue manager has been altered in mqsc as follows

ALTER QMGR CONNAUTH(USE.PW)

AuthInfo has been defined a follows

DEFINE AUTHINFO(USE.PW) AUTHTYPE(IDPWOS) FAILDLAY(10) CHCKLOCL(OPTIONAL) CHCKCLNT(REQUIRED)

Is this a IBM MQ issue? How does one configure MQ to accept and correctly process names with uppercase letters as the OS seems to be doing?