I am writing this to make an official bug report for mining Rich Thorium in Winterspring. I was and am mining all around Winterspring. There is one Rich Thorium vein in Mazthoril dragon cave in western Winterspring. It is located immediately next to the portal markings on the ground inside the cave. Usually me and other players enter the cave via jumping on the mountains and then using the portal markings on the ground outside the cave.
So, this Rich Thorium vein is bugged. I mined it, and it showed me the loot of 1 Thorium ore, 3 Dense Stones and 1 Arcane Crystal. When I finished mining, I received NO loot, despite having enough empty spots in my bags and enough capacity to accept Thorium and Dense Stones. I tried mining again, but it showed me NO LOOT after completing the mining animation and the cast timer for mining of 3 seconds.
Then I relogged and tried again. Then I called a friend to record all, and he even came on his hunter (because his paladin has no mining) to try to mine it himself, and the vein showed empty to him as well.
As evidence for this, I will post the link to his YouTube video recording of the entire thing.