I had existing part and wanted to add an extra hole.

I loaded it into solidworks, edited the sketch for one of the existing extruded cut features

and after exiting the sketch,

everything about the part became invisible except for existing holes with cosmetic threads.

On an existing drawing of the part, all the outlines (in the various 2 dimensional projections) vanished, leaving

only cosmetic thread outlines.

If I select individual items from the tree, those elements of the part are highlighted,

but there seems to be no way to view the object any more, nor therefore to pick-up

on elements within the part for referencing new elements to the locations of old.

The object has acquired invisibility. (Useful for military aircraft I assume)

Notes:

a) This is in a part file, NOT an assembly

b) No change of outline view, ie shaded, with or without edges, show all edges, hide hidden edges etc makes the slightest difference, the part

remains invisible.

c) I've attached the part as a file to see if anyone else can see it.