I think there is a bug with the shard crafting.
I had a stack of 4 Inferno Shard IVs. I tried to craft 3 of them into 1 Inferno Shard V, but it didn't work. I deposited the items to stash, took them back, brought them back to technopriest and this time it worked, but it did not consume the 3 tier IV shards that it lists as crafting ingredients.
I have a footage that demonstrates the issue and steps to reproduce that you can watch here.