Although Adobe Illustrator's type, shape and path tools create sophisticated graphics, some properties associated with these tools can cause newly drawn paths and shapes to disappear unexpectedly from the canvas. For CS versions of Illustrator, commands for the pencil, pen and brush tools can be adjusted to prevent loss of shapes and other types of artwork, and adding strokes or fills can solve problems with disappearing shapes when path tools are used.
Type on Paths
Illustrator's type and path tools work together to create type that flows along a path or around shapes. However, when type is applied to a newly created path, the object delineated by that path disappears. To avoid this, copy the shape and save it on its own layer so that it will be visible when the type operations are completed.
Pen, Pencil and Brush Tools
Illustrator's pen, pencil and brush tools have helpful options which may result in the disappearance of recently-created lines and shapes. Unless otherwise specified, these tools edit or delete recently-created shapes and paths when a new one is added nearby using the same tool. To prevent this behaviour, click on the icon for the selected tool. Under the options offered there, un-check "Keep Selected."
Path Tools: Adding Strokes
Paths and shapes drawn with any of Illustrator's drawing tools may seem to disappear once completed if no fill or stroke has been applied. If a just-completed path or shape appears to vanish from the canvas, check the fill and stroke boxes at the bottom of the tool palette. If both are empty, choose "Select All" (Cmd-A for Macs, Ctrl-A for Windows) to select the entire shape or path, and apply a stroke or fill colour to keep it visible.
The Pathfinder Palette
The Pathfinder palette offers numerous options for adding, subtracting or intersecting shapes that are overlapping or adjacent to create a variety of effects. Relevant objects are selected and buttons are clicked on the Pathfinder palette to create the desired effect, which is applied by checking the Expand button. However, if two or more shapes are selected for the Intersect Shape Area operation, all shapes may disappear after clicking "Expand." Save a copy of all shapes created, or apply the effect to multiple shapes incrementally to avoid this problem.