I don't recall any bugs with the regeneration chambers not being deactivated, but there is not a long cooldown before they come back online. With my ranger on nightmare difficulty I had to run straight for the two levers, and then turn and fire an explosive arrow, jump over a couple walking armours and use a point blank splitting arrow to finish off General Raze (if I knew Way of the Ranger then, just a Splitting Arrow may have been enough). In one attempt I got hung up for a couple seconds when I tried jumping over the walking armours that got close when I stopped to get the second lever, which was enough time for the first chamber to come back on. Another time I was a little far away when I used the splitting arrow, took him down to just a few hit points left, but couldn't get another hit in before he headed to the regeneration chamber.
In the original release with my warrior I could just allow the walking armours to build up and have my creature active to block one chamber, to force him to run for the other, and didn't have to deactivate the healing chambers. I tried that in DKS, but he cheats... a lot (teleporting directly to a chamber, running away while under the influence of a Stun Arrow or in the middle of being hit by Thousand Strikes, etc). In DKS I had to get the levers and then attack right away; any mistake and it was easier to reload and enter the room again, since a build up of walking armours made it that much more difficult to get the levers quickly.
If you are not already playing on casual, you could try lowering the difficulty level.
You could reload a save before entering, and come back for this later, when you have better equipment and can do damage faster.
