I have a problem with Diablo IV. The problem concerns the armor upgrading technique at the Blacksmith - specifically, upgrading is not available for legendary items at the Blacksmith. I noticed that I can’t upgrade any legendary items at the Blacksmith. I can’t upgrade items from the Whispers Tree, legendary items from the Purveyor of Curiosities, legendary items obtained from Nightmare Dungeons, or from other locations. Upgrading at the Blacksmith is not available for any legendary items. And it worked before. The only legendary items I can currently upgrade at the Blacksmith are the legendary items that are already equipped on my character. This confirms that I could upgrade legendary items before. Now it doesn’t work. Upgrading at the Blacksmith only works on sacred items.
Did you try tempering them first before upgrading them?