The only time I've ever had a follow issue in a battleground was when someone else had an identical name to one of my toons.
None of the others would correctly follow that one toon.
Although everyone else leading was fine, and they would follow any other leader.

The Jamba master shouldn't have any impact on follow status.
I like to have Jamba promote the leader to party leader, which lets me queue for battlegrounds as a group or reset instances.
But as far as follow goes, you don't even need Jamba for the IS Boxer follow to function.

If follow functions outside of a battleground but not inside, that is perplexing.
Is your Follow based on the FTL Follow, generated by IS Boxer?
If you're using a Party Leader system (pre-FTL), where the active window is promoted to leader...
And everyone follows the party leader...
And you toggle action bars, in such a way that the leader has non-assist buttons but the slaves are on the next action bar where they cast at the target's target...
In that old system of assist (The L in FTL, which means Focus-free, Target-independent, Leader-independent), once it became impossible to move the characters around to keep groups intact... the assist/follow would fail, because you could not ensure one of your own toons would be leading your group.

A non-FTL assist/follow, based on Focus would work if you really didn't want to use FTL.
But FTL should be working fine, irregardless of which toons are in a given group at one time.

If you're using the FTL follow, I'd attach a copy of your configuration.
Go to File > Copy Profile to Clipboard with account names omitted.
Paste the whole thing (without line numbers or formatting) on www.privatepaste.com
And then copy the link, and paste that in a reply.