The Cannot See Target error has popped up on a bunch of things not just Jadus. That being said I'm a Marksman Sniper and I just killed him about 30 minutes ago without an issue. I got the bug, I re-positioned myself, and then I was fine.
It's just a small bug that the developers will have to patch when they get a chance.
Secondly, as a Marksman Sniper you have no real reason to be using Explosive Probe imo. Tighten your rotation up.. at this level really the only things you need on a fight like Jadus in terms of DPS abilities are Laze Target/Snipe/Ambush/Followthrough *if you have it*/Takedown/Shatter Shot
Of course interrupting his casts when you can (12s CD) and using Cover Pulse/Entrench/Distraction are necessary as well but they don't consume energy if I'm remembering correctly.
When I did him, I sent Kaliyo in first while I took cover. Laze Target right off the bat, Shatter Shot, insta-Snipe, then I should have enough energy to use Ambush and a couple Rifle Shots to keep my Energy where it needs to be, and then repeat and sub in Rifle Shots as my energy dictates, although since the fight is short and they give you breaks to rest & regen, energy efficiency was second to DPS output in this case.
Cover Pulse isn't your interrupt... Distraction is. You should be using Cover Pulse to keep him at range so that you can DPS him effectively.
You have MULTIPLE interrupts...don't forget Flashbang can be used as an interrupt as well.
That leaves...
Flashbang
Cover Pulse *if he's casting close to you*
Distraction
You can even use Debilitate if he's right on top of you. Then you also have Leg Shot if you need to keep him away while you reposition and find a new spot to take cover.
If your using the right gear and the right abilities the fight really isn't that bad and it's nowhere NEAR close to "broken" or "bugged." I for one salute BioWare for having the guts to make solo content challenging. Fights like that do wonders for teaching the class - they demand you know what tools you have and how/when to use them. If you're expecting to sit in one place and spam Snipe/Ambush over and over it's not going to work.