Tangent Space normal maps, bug in RC4?

Hi,
I was overjoyed to see tangent space normal maps in RC1, especially as they appeared to ‘just work’. Then I updated to RC4 - and they’re either broken or there’s a new setting I don’t know about - I pray it’s the latter!

Anyway. My TS normal map used to look like this:
http://cid-7828d8c206911856.skydrive.live.com/self.aspx/Public/Good.jpg

Nice continuity over the shoulder where the UV seam is.

Now, in RC4, it looks like this.

http://cid-7828d8c206911856.skydrive.live.com/self.aspx/Public/problem.jpg
Complete disaster over the seam.

Both maps were made by baking a hi-poly reference model onto the base mesh. I haven’t changed any settings - just updated from RC1 to RC4.

What have I done? And I can’t find a link to RC1 so I can’t get a new working map.

Help!

Good - I’m not going mad, it has changed. Now I just need to update my NWN2 exporter