You may ask why I keep saying to "close other forms first". If you simultaneously have a form open that has a custom UC on it, and also have that custom UC open for editing, the IDE sometimes gets confused and changes all those custom UCs on the other form to PictureBoxes. If your other forms are just sitting in the Project Window (unopened), this never happens.

And this sort of makes sense, considering all the things the Intellisense is trying to do (show you all the properties and methods of everything).