Experience is not collected when clicking on smelting recipes (maybe because it 'bumps out' the items already there and doesn't check for player interaction).

Replication:

1. Begin smelting items in furnace
2. Wait for some/all items to smelt 
3. Click on recipe book
4. Click any smelting recipe

The items in the furnace will return to your inventory, but no experience is gained from the smelted items. No experience sound is heard either.

I cannot provide a video because the file is too big, so here are some pictures that may help.