This is nonsense.
"Seems" is the operative word.
Try running it in the file you linked to in msg#1 looking for 5:00 10 March 2020
Also try looking for 5:00 9th March 2020 which isn't in the list - it returns a value!
Addition after posting:
Attached, that file with a button to run your line of code, and the other two I suggested earlier, and puts the 3 results into K4:M4.
First search for 17:15 9th March 2020; all fine, three similar results in cells K4, L4 & M4.
Second, search for 5:00 10 March 2020; Correct results in L4 and M4, your code throws an error.
Now try 5:00 9th March 2020 for which there is no data in the table; L4 and M4 both display correcly #N/A, whereas your code return a value of 13055! (This is the close on the 10th March at 5am)