Disappearing Feature Class with SelectLayerByLocation_management?

Discussion created by shawn.m.carter on Jun 13, 2013
My first ESRI forums post and it's probably dumb, so apologies in advance.

I have a script that allows me to select a particular construction plan and then select all the water valves and water mains from within that construction plan.  The issue I am having is when I use the SelectLayerByLocation_management command for the water mains, the valves will not be an available option i the Python window afterwards.  Likewise, when I use the same command for valves, the water mains feature class won't be available.  All the other feature classes in the layer are selectable in the Python's just those two that seem to be exluding each other.

Feature or bug?