Yes, I am aware but the engine still support it, there is still a texture group for it and you still have the option to use specular, so I would assume this feature would still work or if it has been combined with another group, update the stat page to reflect this. One way or another, it was not clear and I believe it to be a bug.
Your repro steps are being reported with build version 4.0.1, but your report also mentions engine version 4.12. Would you mind clarifying which engine version you are reporting this issue under? I just tested the issue in version 4.12 but did not get the same result.
Would you mind testing your issue in the most recent version of the engine using the source or binary version to see if the issue persists?