I believe I have found the problem. The macro segment shown above was placed in a button so I could reference it from multiple devices which require the same setup. It appears that when you execute an alias which contais "IF" statements, the variable tetting in the true leg of the "IF" is not completed before the macro moves on. So if there is a subsequent test of a variable later in the host macro it will fail because the variable has not yet been set. A work-around is to place all the contents of the macro in stream with the original device button. This meant I had to duplicate the entire contents of the macro in every device. This is less convenient but it did solve the problem.

If anyone sees something wrong with the way I resolved this please feel free to let me know.