Hi Rithvik ,
Please check with the BASIS team whether they had updated the ESR content after upgrading the PI to 7.3 . This comes as a part of post installation /Upgrade process
1619989 - SPROXY shows empty tree after upgrade to 7.30
1635664 - Compatibility of ESR with PI and SLD in a system landscape
1942289 - Known issues with PI and ECC EHP upgrades
Thanks ,
Manu