Replicator clips when it shouldn't

When I put down an fxReplicator object to make a patch of grass on some angles it gets clipped while the player is still looking at it. Also note my X & Y outer radius. Unless one of these is 80 nothing gets generated. What is the significance of 80 and why is it being clipped? I thought maybe 80 was too big and maybe that's why it was being clipped, so in trying to reduce the size I discovered that one must remain at 80 to appear. I did try reducing the number of billboards and retries which made no difference to this issue. Again, as always, any help would be appreciated. All I've modded in the engine is shadow code as provided by Melv so I haven't touched the fxReplicator code.

In this shot I have moved very slightly and from the player view this whole chunk of the object disappears (see good photo below)

In this shot I have moved very slightly again and the square area is filled with grass again. All this happens while the player is looking at it.