Method 1: Clean Registry and Repair via XLN Online Installer
Open Addictive Drums 2 as a standalone app (outside of your DAW).
Your DAW's plugin scanner might be getting confused, attempting to load an older, incompatible version of the Addictive Drums 2 VST2 ( .dll ) or VST3 file alongside the correct one. Your DAW's "blacklist" may have also automatically marked a previous, outdated version of the plugin as unsafe, preventing any version from loading.