CC4 does not allow me to export BVH files without an error and I do not think I am the only one. This happened on CC 4.5 initially, but, when I updated to 4.52, the problem persisted.

Steps to replicate:

1. Use any character, in my case, it made no difference whether I use CC3+ or a Daz character imported with the appropriate bones preset.
2. Click on File > Export > BVH.
3. Select hip as Root (or leave it default (RL_BoneRoot), again, no difference).
4. Select either Current Pose or Current Animation.
5. Export the file.
6. Receive the following error: Failed to export the following clip(s) as BVH: 6484943704576_TempMotion

I have tried the following with no luck:

1. Changing Target Tool Preset
2. Changing Frame Rate (12 - 60 fps tested)
3. Used Current Pose, Current Animation and added as custom with no success.
4. Used various Root bones, none of them allow for export.
5. Added Prefix and Postfix.
6. Used both CC3+ and Daz characters, no success. (Example that was used for CC3+ was the CC4 Kevin base)
7. Use custom poses from the RL marketplace.

Interesting note, that same TempMotion file name goes over to the FBX file, too. Unsure if that means anything, but the name was in a similar style when I exported it out of Blender from CC4 via FBX.