Calculations using time without dates!

I have a table, called “Work Records”, where I track lessons I provide. 

In column A I record the date of the lesson. 

I record the start and end times in columns D & E, respectively. There may be multiple entries for the same date, with different start times. Start times can be, for example, 09:00, 09:15: 09:30, ….

In column F I calculate the duration by subtracting D from E, within a DUR2HOURS formula. Durations are always whole numbers - no fractions of an hour.

Columns D & E are formatted for time only (Date set to “None”), but when I select a cell in these columns, Actual still shows a date and time. 

In another table, called “Start - Duration”, I want to see how the duration varies with the start time. 

Columns B & C of “Start - Duration” are formatted for time only (Date set to “None”), but when I select a cell in these columns, Actual still shows a date and time (in this case, the date when the table was created). Normally, columns B & C are hidden.

Columns D through G are the possible durations (1 to 4 hours). In cells D2 through G8 I want to calculate the number of times a lesson starts within the period HH:00 and HH:59 and lasts for 1, 2, 3 or 4 hours. I use the formula

COUNTIFS($Start Time,">="&$B2,$Start Time,”<=“&$C2,$Duration,"="&D$1), 

where “Start Time”, and “Duration” refer to columns D and F of the “Work Records” table.

There are no errors reported for the formula, but as can be seen, the calculations show “0”. I suspect this is due to the hidden dates being included in the time-only columns in both tables, which will be different (in “Start - Duration” the date the table was created, in “Work Records” the date the lesson was booked).

What do I need to do to make the “Start - Duration” table work the way I want?

NOTE that I have selected my MBP as the device and Numbers for Mac as the topic, but this is an issue for me with Numbers across the MBP, iPhone and iPad.