- Build the Ribbon Sample addin (Debug or Release)
- Open Ribbon-AddIn64-packed.xll with Excel 2016 x64
- Click the "My Button" button
- Close Excel:

Tried on Excel 2016 x64 Version 1803 (Build 9126.2152 Click-to-Run).
Tried to update ExcelDna NuGet packages to v0.34.6.
If I don't click My Button and just close Excel right away - it doesn't crash.