Hi Mike,
Thanks for your patience.
We have analyzed the shared log files and found that toolbox was not configured during build installation. Please try the below steps and let us know if this helps you to resolve the reported toolbox issue.
1. Close all Visual Studio running instances.
2. Remove the *.tbd files except the toolbox.tbd from the following location:
C:\Users{user name}\AppData\Local\Microsoft\VisualStudio\{VisualStudioVersion}
Note: Visual Studio version for VS 2019 starts with 16.0_.
Example: C:\Users\syncfusion\AppData\Local\Microsoft\VisualStudio\16.0_885430b7
Regards,
Vadivel Natarajan