Suddenly experiencing problems with imported Carrara animations

I’ve been using Carrara with Unity for several years off and on. Generally they work well together but did have to change the way I rigged my characters a couple of times after Unity upgrades. This problem seems to have started sometime after blend shape animation was introduced in Unity.

Suddenly, I’m having trouble with arm and hand animations. The leg animations look OK.
The rig looks good when configured as Humanoid, and responds well with all of the sliders in the muscles window, but the animations look terrible in the animation preview, scene, and game windows.

I’ve reported this as a bug but wonder if anyone else has encountered it. If so, have you found a way to deal with it?

Yes, the characters have IK for the leg animations, but the arm animations, which are the ones with the major problems, are all FK.

I had been experimenting with setting the the bone orientation on the arms based on readings about LightWave, and it really improved my Carrara arm animations in Carrara - but no variation I’ve come up with seems to be of any help with the weird arm rotation I’m suddenly getting with Unity using Mechanim.

I got Unity 4 Pro betta last Fall and had similar trouble, but submitted a bug report, and the problem was corrected. Everything worked very nicely for a while so this is perplexing and frustrating. Nice to have a quick fix!