Some weird /assist /follow targets

[Grundel]

I have a 5 box group Druid tank priest and 3 mages. My wife likes to play with me and when she does she plays the druid tank. and i play the rest. I usually drive with the tank when alone. but i drive from the healer when we play together. and want the mages to to follow me and take my targets for sheep. However Randomly one mage will follow her instead of me. and they randomly take her target and sheep it. I am not using strobe follow. i do use follow after combat with ema. I am using round robin with assist key for sheeping and default