I have created annotation from the labels of a set of contour lines in ArcGIS and used Feature Outline Mask to create a mask layer in order to mask the lines using Advanced Drawing Options and make the contours stand out. Everything works great for a time period and then the masks seem to disappear and the contour lines cross the annotation. Examining the attribute table for the masks implies the all masks are still there but I am unable to see the actual polygons. Strangely enough if I copy a polygon to the mask feature class it will be show up both in the map and in the attribute table. Additionally, I have two sets of masks for annotation: one for the contours and one for isopluvials (rainfall lines). The masks for the isopluvials work as expected. The masks for the contours work briefly, but then stop working and appear to vanish. Has anyone seen this behavior before?