Office 365 Store Version does not recognize Excel COM add-ins
The store version of Office 365 will completely ignore Excel automation add-ins as defined in the article.
This is the cloud version of Office 365 that installs in the Winapps folder. In Excel File-Acccount versions are similar to
Version 1807 (Build 10325.20082 Microsoft Store)
Excel completely ignores these addin entries in HKCU
The only way currently to resolve this is to have users convert to click to run versions so that File-Account displays as
Version 1807 (Build 10325.20082 Click-to-Run)
Please consider updating this or add an entry to the Trust Center that can be configured to allow this type of addin.
This is a major problem. Microsoft wants developers to build what it ambiguously refers to as "Office add-ins" instead of VSTO (COM) add-ins going forward. This is why the Windows Store editions of Office do not support VSTO add-ins. Unfortunately, Microsoft has made it deceptively difficult to determine whether you have the click-to-run or Windows Store edition of Office installed (as of this writing), and not much easier to find the click-to-run edition in your O365 account.
The bigger problem here, however, is that the Office.js API used to build "Office add-ins" is very basic and horrendously incomplete compared to .NET Framework / Office object model used to build sophisticated VSTO add-ins. Therefore, sophisticated VSTO add-ins used extensively in enterprise environments cannot simply be reengineered to "Office add-ins" that support only basic functionality. Unfortunately, professional Office users must continue to uninstall the lightweight Windows Store edition of Office that PCs now ship with and install the fully functional click-to-run edition that supports sophisticated add-ins.
I don't disagree that transitioning from VSTO to Office.js is a good thing, but Microsoft's attempt at a transition has been premature and developers currently do not have the Microsoft tools they need to make the transition successful.