RCT.Plugin.Builder.dll not found

I recently built a new Server 2016 server and installed the SCCM console. We are running CM 1906
I installed the Recast right click tools version 4.2.2007.3601

A few admins who are testing the new server reported the CM console crashing

In the SMSAdminUI.log around the time of the crashes I see the following error. It is looking for a DLL that is not present on these servers. What is odd when I asked each user who reported the issue, they were doing something to a collection, but not using the RCT software.
But the console crashes and this is what I see in the logs.

[33, PID:10980][09/14/2020 08:28:04] :Assembly C:\Program Files (x86)\Recast Software\Recast RCT\RCT.Plugin.Builder.dll not found
[33, PID:10980][09/14/2020 08:28:08] :The ‘AssemblyPath’ assembly (C:\Program Files (x86)\Recast Software\Recast RCT\RCT.Plugin.Builder.dll) was not found.\r\nSystem.IO.FileNotFoundException\r\nCould not load file or assembly ‘file:///C:\Program Files (x86)\Recast Software\Recast RCT\RCT.Plugin.Builder.dll’ or one of its dependencies. The system cannot find the file specified.\r\n at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.InternalLoadFrom(String assemblyFile, Evidence securityEvidence, Byte[] hashValue, AssemblyHashAlgorithm hashAlgorithm, Boolean forIntrospection, Boolean suppressSecurityChecks, StackCrawlMark& stackMark)
at System.Reflection.Assembly.LoadFrom(String assemblyFile)
at Microsoft.ConfigurationManagement.AdminConsole.Common.UtilityClass.LoadAssemblyByName(String assemblyName, Boolean reflectOnly)\r\n

thanks