Hello and thanks!
I am using ArcMap 10.3.1 and working with vegetation data, ESRI grid format. Until recently I have been able to successfully use the "Only show classes that are visible in the current map extent" feature (legend properties>Items tab>Map Extent Options). Now when I check this option, the legend list is cut off, meaning that only roughly 1/2 of the classes show in the legend. I have attached a screen capture of a legend that does not list all of the legend items, leaving off roughly 1/2 of them.
All ideas appreciated!