i have exactly the same problem
i have t4 exploration cruiser and the commander engineering station is bugged - it is only blank skill window there and nothing more - i tryed to sell and to buy a new straship -ee, i tryed 5x ofiiciers -ee
i have noticed that there is something that makes the skill unusable - officers cannot be tought new commander rank skills - it says replaces uknow nodes -- so this is a serious bug
i have posted it ingame - but no reaktion at this time
Aceton skill is trained on some BO's as a space skill, However trying to retrain the BO yields the screenshot below as a result.
This is why you get "Replaces unknown node" when you try to change that skill for space. But when you try to retrain the same aceton skill it shows up as replacing a ground skill. (This is why it does not show up in space at a LT CMDR engineer station as seen in my previous screenshots. The game thinks the skill is a ground skill.
The screenshot here will show you exactly what I'm talking about.
I have a Lt. Com Boff who had aceton field trained by default. The skill cannot be replaced at the trainer it just says "Replaces Unknown Node" and if I try and use it in the Lt. Com station it just has a blank sqaure and the power can't be used.