This is a hole in the SEARCH facility.
You can use the XRef View to get the same info (but obviously not as intuitive).
Page through the XRef View until you find the desired Y output (e.g. Y7). Then look down the list of instructions of where it is used in the Instruction column, and look for OUT (or SET or RST or ...). Double clicking on THAT instruction cell in the XRef table will take you to that point in the ladder program.
We are looking to greatly enhance this SEARCH functionality in Rel 6. Sorry about the missing (and highly needed) functionality.