What kind of follow are you using?

The default game follow.
Normal follow from Jamba.
Or strobe follow from Jamba?

For /Follow (warcraft follow) or Jamba Follow (not strobe follow), all you need is any movement key.
From up/down arrow to W/S or strafe left/right, depending on how you have your keys set.

If you're using strafe, then you need the Jamba command to stop that.
Otherwise once you break follow, they'll start following in a very short while.