I have my answer...
Logix 5000 Task Monitor tool v3.4.x.x and all prior versions are not compatible with engineering workstations that have v30 or greater of Studio 5000 Logix Designer installed.
Logix 5000 Task Monitor v3 is not supported with Microsoft .NET Framework 4.6 and greater.
Workaround
Install Logix 5000 Task Monitor tool v3.4.x.x on an engineering workstation or virtual image that does not have v30 or greater of Studio 5000 Logix Designer installed.
Alternatively, uninstall:
• Studio 5000 Logix Designer v30
• RSLinx Classic v3.90
• FactoryTalk Services Platform v2.90
• Microsoft .NET Framework 4.6
Next, install RSLinx Classic v3.81 and FactoryTalk Services Platform v2.81.
So to make this work - uninstall the current version of Studio. Great... just great.