Selected Answer
I admit to not fully understanding your problem but I feel it is self-created by your lack of understanding of Excel's handling of Date and Time. Your Helper columns seem to destroy your data. Please try if the following helps.
Entering =NOW() in a cell and formatting that cell as General will display a number like 43275.83088 in which the integer indicates a date and the decimals the time. Different cell formatting will change the display. To get a feel for it, try dd/mm/yy hh:mm or d mmm yyyy hh:mm AM/PM or simply ddd (all Custom formats). The display in your Helper column OA could be simply produced with a cell format of hh:mm AM/PM without changing the cell value. However, if you wanted to change the value to exclude the date the simpler formula to use would be =MOD(N2, 1) instead of =IF(ISNUMBER(N2),TIME(HOUR(N2),MINUTE(N2),SECOND(N2)),"").
Of course, when you exclude the date from the cell's value you lose the ability to calculate time differences that span days, such as 11 pm to 1 am (next day). Similarly, counting values between, say, 43275.50 and 43275.75 (12 noon and 6 PM on June 24, 2018) would be a simple matter. The thing to understand is that the cell values remain the same whatever the cell format prescribes for their display.
I would also urge you to replace range references like 'Raw Data'!$M$2:$M$9999 with a named range like TaskNm. Your formulas would become must easier to read, much shorter and you would have the added bonus of being able to define the named range as dynamic so that it grows and shrinks with the number of rows actually used, and that would make your worksheet calculate faster.
Please see how far you can get with the above advice. Let me know where you get stuck after implementing a system of dealing with Date/Time values the way Excel intended that you should.
