More than one Private Location was defined to the Workspace used for BlazeVSE.
Release : SAAS
Component : BLAZEMETER MOCK SERVICES
https://guide.blazemeter.com/hc/en-us/articles/360012819678-Introducing-BlazeMeter-Virtual-Service-Environments-Introducing-BlazeMeter-Virtual-Service-Environments
Note: We do not support sharing of private locations across Workspaces for BlazeVSE. It is recommended that a new private location is created for each BlazeVSE within a workspace.
Once one of the Private Locations was removed, this resolved the error.