It seems the bug is tied with the damage bonus that feedback loop has, when you switch out gear or skills sometimes. That 20s damage boost duration seems to interfere with the backpacks 10s cooldown. It happens when I run my revive + seeker build, then switch my seekers off to the firefly or other status applying skills. So it's the damage boost of FL that's causing the issue, it has some problem when tinkering with gear & skills while HW is in effect.
The damn thing is bugged again, as long as the Feedback Loop is active the cooldown is not reduced when you use or cancel the other skill.
I tried swapping a few pieces of HW gear with others, even equipped other loadouts then back to HW ..... is NOT working. Only after the Feedback Loop buff is off you can use/cancel a skill to reduce the other one's cooldown.