I'm still strugglng with automating my ore processing.
It's really a larger problem with Gregtech item pipes and sorting in general. They don't really deal well with any kind of filtering. I'm trying very hard not to resort to using another pipe system, such as Project Red's transport pipes or Thermal Dynamic's Itemducts, since I feel I ought to be using Gregtech's expensive pipes and filters to stay in line with the overall difficulty level of the mod.
If a chest buffer sends its output into a pipe, if the destination for the first item in the chest is full, the system locks up. The item goes into the pipe and stays there, and the item in the pipe prevents the chest buffer from sending out anything more. The same thing happens if there are no valid destinations for the first item in the chest buffer.
If the chest buffer is directly connected to another machine instead of using an item pipe, this doesn't happen. Obviously the "full" case still results in a delay, but if the first item in the chest buffer can't go, the chest buffer chooses the first valid item instead of locking up. For example, if a chest buffer for an ore washer gets dusts because the macerator created some dust, that's fine. The first crushed ore goes instead, no matter how many dusts are ahead of the crushed ore.
If chest buffer is sending out logs, and the first item attached is a Type Filter Buffer set to logs, and that type filter is full, the system locks up, even if there are other things in the chest buffer than could move. If there's a sapling after the log stack, for example, it stays put even if there are valid destinations for the sapling. On the other hand, if I replace the Gregtech item pipe with a Thermal Dynamics itemduct, the logs wait but the sapling moves.
So the simple solution is just to use Thermal Dynamics Itemducts. Which cost 1/6th what Gregtech Item Pipes do, because it's 2 Tin + 1 Lead -> 6 Itemducts intead of 3 Bronze -> 1 Item Pipe.