3366706 - Time Off Request (TOR) creation blocked by certain past period TORs

When employee navigates to "My Time Off" from the WT&A Dashboard and then to Time Off Request creation screen, the bank balance graph fails to load saying "Error loading graph data":
  

Further, trying to proceed by clicking on the Next button causes a server error message dialog to be displayed: 

Server logs (specifically one of the server_log.txt files accessible through Dashboard > Server Administration > File Browser) may have one of the root-cause error messages/stack traces similar to below.

SAP Absence & Leave Management by Workforce Software (Version 9.4 +)

KBA , XX-PART-WFR-ACT , SAP Absence & Leave Management (ACT) by Workforce Software , Problem