Did you try to Sync Annotations, rather than Extract Metadata?
Unfortunately, the only way I know of to export the info back reliably is to use DNG.
I do believe I tried Sync Annotations, but I didn't expect it to do anything because I don't believe IVMP will write to anything Canon RAW Files via an XMP sidecar unless the extract metadata is used. I also understand exactly what you are saying with DNG, however Idimager and ACR seem to work fine writing to the same XMP sidecar. I guess I just feel like the same would be a reasonable solution for IVMP. I just can't jump on the DNG push because Bibble is one of my weapons, I just like to keep those ACR settings if I can when I use it. Thanks for the confirmation.