”Hextech Crafting failed”
We don't know why it fails. We know these items don't need testing anymore (already on Live and/or retired), so Riot won't fix them on PBE for the foreseeable future. As such, they don't need to be reported. This happens to the following pieces of Hextech Loot:
Certain Summoner Icons and Ward Skins.
Glorious Champion Capsules.
Regular & Masterwork chests (since 12.09).
4. ”Why does Riot not fix X?”
Short answer: “Because it's PBE.”
Long answer: these bugs have no priority and thus won't be fixed (anytime soon). This can be for the following reasons:
The content is already on Live (or has already left Live), and therefore needs no more testing on the PBE.