OK, I figured this out on my own tonight after Drakkun's comments. I use /assist focus commands as my primary means of doing everything instead of assisting by party number or name. However, when you're not in a group, the normal focus commands that I was using in my macros were not working.

However, the focus command will work if you use the /target command first or just click on the toon you want as the focus and then set focus (e.g. /target killer and then /focus Killer). Then all of the other commands seem to work out OK. I also use the mod Sticky Focus, but I don't think that has anything to do with it.

Johnny