DPP does currently support the CR3 format but because the Canon CR3 format is mainly based on the ISO Base Media File Format (ISO/IEC 14496-12), with custom tags, therefore it isn’t based on the TIFF format any longer. Unlike TIFF the offsets are not absolute, they are relative to the start of the data block for each directory.
It may take a while but is a far superior format to the CRx TIFF based formats because it is a QuickTime-based format that gives lossless compression with far superior compression and the C–RAW format is 40% smaller in file size than conventional RAW, and it corresponds to in–camera RAW development and digital lens optimizer.
So I would suspect that it may take a little longer as even the major RAW processing applications don’t support it. I simply recommend to others that they use DPP to generate a TIFF and process with that in the meantime.