When I activate the Oraculum, three specific unconscious witches instantly die. How do I avoid this?

In The Royal Conservatory, the following happens after I've rendered everyone in the building unconscious:

(a) I check my Stats for the Current Mission and they say:

Spotted by Enemies .... 0
Assassinations ........ 0
Nonlethal Takedowns ... 27
Total Kills ........... 0

(b) I place the target in the Oraculum and turn it on.

(c) I check my Stats for the Current Mission and they say:

Spotted by Enemies .... 0
Assassinations ........ 0
Nonlethal Takedowns ... 27
Total Kills ........... 3

I have identified the three unconscious witches who die:

• the one with the gray vest and white shirt in the turtle courtyard
• the two waiting to ambush you in the alley to the right of the first Wall of Light on the level

No matter what I do with these three unconscious enemies -- whether I move them to another spot, swap them with other witches's unconscious bodies, etc. -- they die as soon as the Oraculum is activated. I even tried carrying one of them over my shoulder while turning on the Oraculum, but of course the game makes you put down the body when you flip the switch. Then you get to watch helplessly as she bleeds to death.

Is there anything that can be done to avoid this, aside from writing to Arkane Studios and asking them to patch the game?

This appears to be a bug in the game. There are a few YouTube videos out there that highlight this moment happening to other players as well (a quick Google search of "witches die the royal conservatory dishonered 2" returned said results).

One solution that seemed to have worked for someone was:

Locate the witches that are dying after activating the lever, then shoot them with another sleeping dart before pulling it. For me, they still died, but they didn't count towards the kill counter.

(Taken from the description of this video)

It looks like another player of the game (see Grulien in the link) tried the fix mentioned above and it works, but in their case, they had 6 witches dying on them.

Other than that, it appears to be a known bug among the players of the game, and there doesn't seem to be much you can do until a patch is made.