Conditional Formatting Bug
While selecting an area in a column and using the rule "Cell that only contains > Cell Value > less than > any specific value written (in time format) > Text Format (Select Color) > Ok", but it turns out that even if I don't put a value in any cell of that selected area in a column, it is coloured whereas the same is not the case if I select the instruction as greater than instead of less than.
Sergei Baklan commented
Blank cell is considered as zero if you compare the numbers. Dates in Excel are actually sequential integers where 1 is equal to 01 January 1900. Thus any blank cell is less than any date.