If you missed the announcement on the VSTO Developer Portal, the team released a tool called AddInSpy that helps diagnosing problems with Office Add-ins. Andrew Whitechapel talks about it on his blog here.
Also check out and download the VSTO Power Tools which Andrew, myself, and the team has blogged about before. This download is packed with tools that make your life much easier when developing Office solutions. So if you don’t have them already, what are you waiting for? Download AddInSpy and the Power Tools now!
Also stay up to date with announcement, videos, downloads, etc from the team by visiting the VSTO Developer Portal.
–Beth Massi, Visual Studio Community