Currently (at least in 10.4) the move symbol up/down the symbology order screen greys out when two or more symbol cateogries are selected. Sometimes I work with layers with up to 100 different symbol categories within a single layer (like a surface geology layer) and re-ordering the symbols take a very long time. I have to induvidually move one layer at a time.
This is not about the drawing order, but it's about the symbol order in the legend, or the table of contents.
So can we have the ability to move in bulk multiple symbol categories up and down at the same time?