I've been having this same issue as well. I did a search and went through some of the results, and most of what I've found involves using focus, which is actually what I was kind of hoping to avoid. I didn't want my primary macros (follow, assist) to rely on focus in case I wanted to use it for other things.

What most people seem to do though, is set the focus to their secondary target, or even have specific buttons mapped to focus the next target so they just hit that button to renew focus, then continue operating as normal. Definitely a viable solution.