Since this is GD...
Maybe there was some other junk left on the anvil and that ruined it?
If you didn't make a mistake, nothing should have been destroyed. Besides the possibility of a bug, a few things could have caused it that I know of.
-You ran out of one material at the end of a batch. When you tried to make another, it saw only some of the things and assumed you got it wrong. Then it destroyed materials and possibly things you had already made.
-you clicked the wrong item in the menu (done it myself few times)
-the table was overloaded and it didn't read in all the materials (it doesn't sound like it in this case if you only had 50 things). Thinking you were missing something, it destroyed a bunch.
I'd suggest bulk mode (again). AFAIK you don't lose materials with misclicks, wrong things or whatever. Only what you use up when you ( try to ) make something.
Explaining how to research really would take the whole point out of teaching people how to do it in game. It isn't hard to figure out with a little...research.