I was working with LR & C1 tonight and ran into what seems to be a "known issue" - the "use anywhere" DNG files that come out of LR aren't always recognised by C1.
Then it's all C1's fault and you need to contact them about this. Like TIFF, DNG is a free and openly documented file format of Adobe's. If C1 can't read it correctly, it's their bug.
IF the data isn't raw (or linear raw data), there are no reasons to export DNG instead of TIFF. DNG doesn't equal raw.