it is impossible to clean the tholian ship of all the nakhul; i tried 4 times. first time, i have succeeded to reach the last room, but the last wave of nakhul is never came (3/4); the 3 other times, I was stuck in the consoles rooms, impossible to complete the objective (destroy the nakhul raiding party).
And Skavrin has always the same bug when He wear the 23c ev suit.
edit: it finally worked on the fifth attempt.
the devs need definitely to check this mission. in my opinion, the problem comes from the nakhul ability when they create red shadows (I don't know the name)