Gents,
with the latest update on 1.5.3 beta the ADF started to work as intended again.
As I did not alter the Huey at any time (apart Skullz Huey sound Vers 2.5....and of course tested without this sound mod as well) I have to guess that in some of the earlier updates something was messed up.
Resumeé: it works again, issue resolved for the time beeing