Well ... maybe this is due to the fact that Cyclone IV is new.
When Cyclone II was released, we still used Cyclone I as the Cyclone II was still not available for a while only some parts could be delivered.
When Cyclone III was released, we still had to stay with Cyclone II as the Cyclone III was still not available.
Now Cyclone IV is released and Cyclone III is available ...
The story is always the same with new products, it takes some time until they get available and it is good to ask an FAE what parts will be available first or what the main stream will be