Well just and an interesting encounter in Ker'rat today. As usual when some Federation player getting himself involved with the Borg and some cowardly Klingon starts blasting away thinking they got some easy kill.
After a quick evasive and distancing myself from the Borg to take out that new guy (that I never seen on the Klingon side before) that attacked me in a BoP, I realized my shields were not recovering. I took a look in the spec page and saw this:
Yeah that is going to take some doing to get back to even keel. That negative number looks like the US deficit number. I would be surprised if it is a combination of shield neutralizer and BTSS or phaser proc. Using the graphical ques in this game a re hit or miss.
I've had this happen to me in kerrat a few weeks ago. I was flying around for a few minutes without even realizing my shields were borked. They only way to get them back up was to let the borg kill me and they were back to normal after respawn. I suspect it's some kind of bug with the borg shield neutralizers and maybe some other powers on top of that.