In this case, first verify in the upgrade logs for below statement.
[echo] Upgrading from Pega-RULES product version 07-10-18.
As the above log specifies the 'Upgrading from Pega 07-10-18' version, hence the upgrade script skipped the table mapping step. In normal scenarios, this version should be older versions of PRPC like 6.x,5.x, etc.
We encountered this issue, due to re-run of rules upgrade.bat (instead of resume.bat), as the rules upgrade failed for the first time.
This issue resolved after re-triggering migration and rules upgrade steps.