VS2017 vsto FatalExecutionEngineError on Start Debugging

I've been tearing my hair out with this problem for the last 2 days. When I try to start debugging my Excel 2013 workbook VSTO project, as the project is starting up, I am getting "Managed Debugging Assistant 'FatalExecutionEngineError' : 'The runtime has encountered a fatal error. The address of the error was at 0x725551d2, on thread 0x267c. The error code is 0xc0000005."

Because it's not allowing the project to even get started (I've set break points at all apparent start locations), I can't figure out what is causing the problem.

This is a project that I have used successfully for several years, the last time was in January of 2019.

I've tried creating a new project, but it gets the same error.

This has been on my laptop at work, when I tried at home last night on my desktop I'm getting the same errors. No Excel projects will start up in debugging.

I've tried uninstalling and re-installing Visual Studio as well as Office 2013.

The only thing that has changed is that I have installed all of the VS updates as they become available (seems like every week or 2).

I just now tried this: When I open the Excel worksheet from the bin folder, it appears that everything works the way it's supposed to. So, only when I use the debugger from VS do I have the issue.

Thanks for any help.