VST search become case sensitive after apply the HF.
Release : 14.3
Component : IdentityMinder(Identity Manager)
Issue has nothing to do with HF but the property DisableExplicitConversion was added to the environment at other time.
Remove DisableExplicitConversion or change the value to false.
Please refer the doc for further explanation of the property
https://techdocs.broadcom.com/us/en/symantec-security-software/identity-security/identity-manager/14-4/configuring/advanced-settings/business-logic/miscellaneous-properties.html