I think i have found out what the bug is with FP7's popping.
Two things: If you use another forest object as an exclusion area, it is buggy and will pop in and out all the time. Just don't use this for animation would be my work around.
and this memo gave me a clue for another issue:
"In Forest Pack 7 and above, it is no longer necessary to manually select the camera used for culling. Instead Forest Pack will automatically uses the last camera view from the viewport or render. This does not include non-camera views such as perspective and orthographic cameras, if you switch to one of these views, then the last used camera view is retained."
If you have another camera than the camera you want to render up when you send the render via batch, it will render the wrong culling. This used to work fine in fp6 but now you need to make sure you have the correct camera up before sending jobs from batch to a the local machine. At least I THINK this is the problem.