ProRes codec should work, but error -12906 means the decompressor cannot find the right decoder.
Can you please provide a short portion of this video, so I can check why this happens, and if there's a workaround?
Please upload the video to a file hoster or, if it's not too big, send it via email to me at eberhard (at) coremelt.com.
Thanks for the reply. I would upload the clip, but I know for sure it is not the clip that is the problem. I get the same error on any clip, any session. And some of these are clips that have worked with previous versions of Lock and Load X.