Show Visualizers Error "could not load this custom viewer"

I had the same issue in VS 2015 and none of the answers here helped me but I found an issue on github that described my problem.

The solution, or workaround might be more accurate, for me was to turn off the option "Use the legacy C# and VB evaluators" that I (apparently) had turned on in Tools -> Options -> Debugging -> General.

Try the following.

-Go to Tools->options->Debugging->Plz Uncheck "Use Managed Compatibility Mode"