Hi, thanks for sharing this issue.
The problem here is in the VSIX project template itself. This project contains a declaration as follows:
<CopyOutputSymbolsToOutputDirectory>false</CopyOutputSymbolsToOutputDirectory>
This breaks NCrunch's instrumentation, because the instrumentation relies on having a PDB file in the build output directory.
To fix this, change the code as such:
<CopyOutputSymbolsToOutputDirectory Condition="'$(NCrunch)' != '1'">false</CopyOutputSymbolsToOutputDirectory>