Those fiber optic lines only work 50-60% of the time. Often the drones are carried 20km on foot into position which sucks as you know half the equipment on your back won't work.
How do they not work? Just fail in transmitting data completely? Do you have a link to learn more about this?
Cable breaks
That's right. It is just thin glass.
Well, there's a difference between breaking and being broken. I wouldn't say 33% of all B-17s "didn't work" because they were shot down.
Also, those drones are essentially guided projectiles, and not even particularly expensive ones at that. What percentage of projectiles do you imagine successfully connect with their targets in combat?
That's exactly what I mean though. If you miss the target with your rifle, would you call that "bullet not working"?