In Qlik Sense November 2017 release, whenever using the Excel UDC to add custom attributes to existing users, the attributes do not get added. It only works for new users.
Here are the replication steps:
1.Create local user on Qlik Sense server.
2. Login and access Hub with user to validate authentication and token allocation works.
3. User is now listed in QMC>Users
4. Excel drivers and setup done as described in article 000037143
5. UDC setup with directory named identical to local hostname.
6. Sync UDC, which fails. From UserManagement_Repository log, the below error is found.
ERROR  [Microsoft][ODBC Excel Driver] Undefined function 'LOWER' in expression.
7. Delete local user from QMC > Users
8. Sync UDC, which now is successful
9. Validate group attributes in QMC > Users
10. Login to Hub with local user
The problem is that 'Microsoft Excel Driver' is not recognizing LOWER() function used when filtering for existing users. According to Microsoft's ODBC documentation, the supported functions are LCASE() for lower case and UCASE() for upper case. UPPER() and LOWER() are 'Microsoft Access dBASE' specific functions.
This is a bug and will be fixed in April 2018 release.