there is a suggestion that its bugged and not showing as trainable any more.
Its definitely bugged. Whenever I try to train BOs on my sci captain, one of two things happens:
Sci Team 3 doesn't show up in the list of trainable skills (but other's I've unlocked do)
All the skills I can train appear twice in the list. On one, all the officers (even Sci) are greyed out, on the second the sci officers show as trainable, but clicking on the select circle and then hitting training produces no behavior at all. Sci Team 3 does show up in this situation, but is bugged like all the others.
Also, training of the other skills I've unlocked is very lagged. Even tho it lets me click thru all the buttons to train my other sci skills, often the training won't "complete" (ie never appears on the officer). Tho this may be a more general bug, as my KDF Tac captain trained a BO in target optics III, and it took 5 minutes before it appeared. The server did not seem especially laggy either.