DeepSkyStacker issued a warning in their 4.2.5 release notes regarding recent changes to Libraw. I thought it would be prudent to share this insight to get ahead of any similar issues we might encounter.
They wrote

LibRaw 0.20 has introduced a change that primarily affects users of "older" Canon DSLR cameras and FujiFilm X-Trans series cameras (older includes the EOS 60D and 60Da)!

The change is to increase the size of the frame area of the image that surrounds the "user area" so that top and left margins are an even number of pixels. The resultant image that DSS extracts from the RAW file will be reduced in width, height or both by one pixel. As result the Bayer Pattern (CFA) used for de-Bayering the image also has to change.

Unfortunately the LibRaw developers won't say exactly which cameras this change applies to save to say that it is not a large number. Other have reported that at least the following cameras are definitely impacted by this change:

EOS 1D Mark IV
EOS 5D Mark II
EOS 7D
EOS 60D
EOS 550D
EOS 600D
EOS 1200D

If your camera is one of those affected, you will not be able to use any existing master frames produced with DeepSkyStacker 4.2.4 Beta 4 or earlier releases as they will not be compatible. You will need to delete and re-create your master frames from the original darks, flats etc..