Solution
The LabVIEW Multisim Co-Simulation plugin is no longer maintained by NI. The last compatible LabVIEW version, that supports this function is the LabVIEW 2016 32Bit version.
To determine which LabVIEW version is compatible with your current Multisim version, you need to reference the Multisim Context Help. For further detail, refer to
Multisim>>Help>>Multisim help>>Contents tab>>Simulation >>LabVIEW Multisim Co-Simulation.