CVI - BP System Conversion to S/4

We are in System Conversion to S/4 HANA( 1809 FPS001), before DMO, CVI related tasks are in progress. Custom Screens are developed for Customer and Vendor both since in Old transaction these screens were present CVIS_EI_EXTERN was enhanced and guided code from note#2309153 was followed. However still added Custom Screens are not populated both for Customer and Vendor. Moreover, Customer specific screens are getting displayed for Vendor as well. Has any one faced similar issue(s)?

Referred https://archive.sap.com/discussions/thread/3935129

Regards

Mohinder