I happened upon a bug in the Hegemony base cargo / crew purchase interface.
There were duplicate stacks for every crew rank all at 0 counter. Ctrl + click a 0 stack replaces your own stack by 0, making you lose your current crew.
Buying more crew from a proper stack is okay, unless you Ctrl + click it or sort your cargo.
Also, while in space, I could Ctrl + click any 0 stack, and from the jettison screen Shift + click a 0 stack making it a functional 1 stack. The original 0 stack was still left in the cargo.