In the Kronos release the required skill for Drone Link Augmenters was changed from Combat Drone Operation to Drone Avionics. This was done without ensuring that players who fulfilled the skill requirements of those modules would still do so after the change. In this patch we are bumping up the level of Drone Avionics for all players to the same level that they had Combat Drone Operation when we deployed Kronos. Players who have trained Drone Avionics in the meantime will be given unallocated skillpoints instead up to the amount that their skill would have been adjusted.
What happened instead is people found that their Drone Avionics decreased because of the split in Kronos that required you to only take your Scout OR Combat Drone Operation to 5, so Drone Avionics is now showing you your pre-Kronos Combat Drone Operation skill level.
CCP RubberBAND has confirmed this bug and it is being investigated:
I have confirmed that the skill was incorrectly lowered for some players. It was meant to be a bump. Currently under investigation and added to the known issues.