Custom property is not visible for the pipeline in the BizTalk Admin Console

Unregister your pipeline component from Visual Studio tool-box.
Un-Deploy from GAC your pipeline component assembly.
Delete the your pipeline component from the <BizTalk Install Folder>\Pipeline Components directory.
Close all instances of Visual Studio.
Open your Custom Pipeline Component solution and rebuild.
Copy your Custom Pipeline Component assembly to <BizTalk Install Folder>\Pipeline Components.
GAC your custom pipeline component assembly.
Register your custom pipeline component in Visual Studio.
Try to drag your pipeline component to the pipeline.