By the way, bug reports don't work like this: you are not providing basic information (OS version, Lightroom version, DNG version and recording mode, FastRawViewer version) that would help us to reproduce the message, not even the link to the DNG file in question is present.
Have you tried to update to
Have you tried to update to FastRawViewer 2.0.8?
https://www.fastrawviewer.com/blog/FastRawViewer-2-0-8-Beta
By the way, bug reports don't work like this: you are not providing basic information (OS version, Lightroom version, DNG version and recording mode, FastRawViewer version) that would help us to reproduce the message, not even the link to the DNG file in question is present.