I attempted to use a potion last night and it had two odd behaviors:

• Upon consumption entirely deleted itself - no vial was left. Drinking a 'blank' vial with only water left the vial as intended.
• Potion effect(s?) did not occur. 

While it is possible this potion was a faulty one, I believe it was from the same batch as working ones, and was from a very experienced potion crafter.