I had the same problems, with no practical help from the DxO support. I have a fully manual Samyang 14mm, Canon mount, with no chip glued,.
I have found the exact sequence of tags and values for Exiftool in order to modify the exif for any CR2 image.
Eventually, the DxO module is cheated, and the image is fully corrected.
I include two JPEG images, obtained converting the same original CR2 file, but without and with exiftool correction.
If someone is interested I can post the exiftool exact syntax of the needed additional tags.