Iokath Walker Health Bug

So, it looks like there's a bug on Iokath since the Onslaught patch that doesn't buff the health of a player when using a walker. This is absurdly annoying since walker usage is required for story progression. I managed to get through the first bit of it, but I'm stuck on the Showdown on Iokath mission where you have to defeat 3 Iokath Sentinels. With the lack of a health buff, though, you're lucky to get off 2 abilities before dying.

This mission is, literally, impossible to progress through.