If ActiveX controls remain blocked even after removing encryption from your sensitivity labels, several factors could be contributing to this behavior. Here's a comprehensive overview based on Microsoft's official documentation:
Office COM Kill Bit Blocking Specific Controls
Microsoft Office employs a security feature known as the COM Kill Bit, which can block specific ActiveX controls from running, regardless of other settings. This mechanism is designed to prevent known vulnerable controls from executing. Even if encryption is removed from a sensitivity label, a control with its CLSID listed in the registry under the COM Kill Bit will remain blocked.
Reference: Security Settings for COM objects in Office
ActiveX Controls Disabled by Default in Office 2024
Starting with Office 2024, ActiveX controls are disabled by default across applications like Word, Excel, PowerPoint, and Visio. This change enhances security by preventing the automatic execution of potentially unsafe controls. Users can re-enable ActiveX controls through the Trust Center settings.
Reference: ActiveX controls are disabled by default in Office 2024
Trust Center Settings and Protected View
Office's Trust Center provides settings that govern the behavior of ActiveX controls. If the setting is configured to "Disable all controls without notification," all ActiveX controls will be blocked. Additionally, documents opened in Protected View—such as those downloaded from the internet or received via email—will have active content, including ActiveX controls, disabled until the document is trusted.
Reference: Enable or disable ActiveX settings in Office files
I hope this information helps.