We have been working on the resolution of a serious exploit in game which has led to certain consequences that we wanted everyone to be aware of.

A hot fix has been recently applied to the alchemy profession, with regards to discoveries. For the time being, we have disabled all chance of a discovery, until we can implement the proper fix through a patch, as we can not resolve this matter solely with hot fixes.

We apologise for the necessary but temporary removal of discoveries, and are working to have them re-implemented with an upcoming content patch.

26/04 Update:

This will not only be fixed in patch 2.1, but from then on, alchemists will also have a significantly higher chance of making discoveries.
Yep, emphasis on the word significant.

The original post of this thread has been updated :-)