I'm running Sudoku v1.6.11.0 and have noticed that the candidates in other cells don't change back from red to blue when you UNDO a move or change a number that has been incorrectly entered in a cell. The color seems to change from blue to red correctly as candidates are eliminated, but they don't change back if you make a mistake or explore different solutions.
Have you seen this problem?
I've tried re-installing v1.6.11.0 - no change. Previous version (1.5.xx?) did not behave this way.
Thanks,
Tony