Are there any known bugs in the MapInfo Writers that affect the styling of polygons?

I am reading in 89 TAB files (geology polygons) doing a bunch of stuff, combining them and writing them out as TAB, GDB & SHP. I'm extracting both HEX and RGB values and adding them as attributes to the datasets to facilitate attribute based styling. The output RGB, HEX values match the input values. Unfortunately, the MapInfo writer(s) are outputting the incorrect colours i.e. mapinfo_brush_background and mapinfo_brush_foreground values. An inspector just before the writer has the correct values, but the final TAB file does not. The strange thing is that when I filter out 3 polygons for testing they output with the correct colours. It just goes wrong with 158,000 polygons. Any ideas?