For me it was the Raldbthar shard that was identified as Glowing glass shard instead of Aetherium shard and as such never counted for the quest, and it didn't work to activate the entrance to the forge either. I fixed my problem by typing setstage DLC1LD_Misc 30, this set my total number correctly to 3 even if I had 2 Aetherium shard + 1 Glowing glass shard, then when recovering the last Aetherium shard the count was correct 4/4 and Katria said to look for the forge, the forge wasn't pointed on the map but Katria's journal says it (location 5), after getting there Katria said to put the shards on the device but the device was saying that I had nothing that could fit ( my Glowing glass shard didn't work)... anyways to move on from this point I had to set the stage with the console, setstage DLC1LD 160, then setstage DLC1LD 170, then setstage DLC1LD 180 and finally setstage DLC1LD 185. At this point the lever should be up but it was underground so I had to use the code TCL to go underground and activate it, once this was done everything went as it should. I'v lost a lot of time reloading previous saved games but the shard in Raldbthar was always labeled Glowing glass shard instead of Aetherium shard, for me it was impossible to finish this quest without using the codes. In your case you probably need to setstage DLC1LD_Misc 20 (if not try 30, 40 or 50 till you get 4/4 shards), you'll never get it but then you can setstage DLC1LD 160 and find the entrance to the forge (south of Ivarsteed) hopefully Katria will be there and you can proceed like I did, type the code then go see Katria, if nothing new type the next code.