On Catalog task form after 'Source Request' button is clicked, the source request UI page that gets rendered does not display any data.
Instead it looks like this,
Following records has been customized which caused this issue
1) UI page: 'source_request' -> https://<INSTANCE_NAME>.service-now.com/sys_ui_page.do?sys_id=9b36007b37c13000158bbfc8bcbe5d69
2) Script Include: 'ProcurementUtils' -> https://<INSTANCE_NAME>.service-now.com/sys_script_include.do?sys_id=378ec0bb37c13000158bbfc8bcbe5d17
3) Script Include: 'ProcSourceRequestManager' -> https://<INSTANCE_NAME>.service-now.com/sys_script_include.do?sys_id=b520d0bcff0302003706ffffffffff5c
After reverting above mentioned customized records to OOB version, the issue got resolved.