If the Excursion funnel is a prefab it's possible the prefab has a leak.
Attempt a compile with the prefab in the map (it won't finish most likely, but you still need to do it) and then go to Map-Load Pointfile. That will show you where the leak is. Just because it's on a prefab doesn't mean you can't fix it, though you may have to ungroup the prefab first (not sure whether prefabs are automatically grouped or not).
For the fizzler make sure that you have 'Physics Objects' checked on the flags tab. Same problem caught me out at first.
The reason you were getting leaks before with the first funnel was likely because of func_details. The prefab I use used func_details as the wall around the funnel model. Func_details can't be used to seal the map so in the compilers eyes, you had a giant hole in your map. I am just making assumptions though so sorry if I am mistaken.