OK experts here's an InstallShield puzzle. I think recent Windows 10 updates are affecting this, but I am not sure. We have an application that installs to "Program files (x86)" folder. Our customers have been installing our application for years with no issues. Included in the install is a custom .exe application (written in c# .net) that performs a few registry read/writes to the HKCU tree created by us. Recently the exe included in this custom action has been failing to perform a simple read of the registry tree. But after the installation is finished we can right click the custom action exe that is included, run as admin, and it will perform all functions without fail. We are using InstallShield 2016 Express version. The application is written in c# .Net using Visual Studio 2017 Pro. All applications are code signed including the custom exe. We have "Deferred execution in System Context" setting for the In-Script Execution settings for the custom action. The custom action is located in the "After register Product" section. What am I missing?