Its supposed to fuse as many as you can, so it would appear  for some reason it didnt work, and something is bugged.

Perhaps because you had "used your stock " it was telling you you had none, which in a way was correct, as you should have had the fused gems instead.

If I had found this I wouldnt have tried the same thing again with materials.

You tried logging out and back in, did you also clear cache?

If this doesnt work you will have to wait to see if the administrators can confirm things, fix it ,and give you your gems and materials back.