5 minute scan rate historic logging not logging all intervals

I have a simple test expression integer tag setup whose expression writes the current HHMMSS into it every second (e.g. using now(1)) as an integer value, e.g. 131042 for time 13:10:42.
I’ve setup a scan class as below that I’ve set the Historic Scanclass to in the tag:

While I’m seeing most 5minute intervals being logged, i’ve noticed that there are some times where this has been skipped. See the screenshot below, but ignore the values before 112037 as these were me testing. You’ll notice that the record after 120045 skips to 122045 (i.e. 3 entries are missing for 1205xx, 1210xx, and 1215xx). Why would these values have been skipped?
Also, can I get this to synchronise to on the hour? e.g. all seconds should be 00, 120500, 121000, etc.


Thanks in advance.

Is there anything in the gateway logs during those times that were skipped?

Hi Kevin,
The only log in the gateway log between those times, 12:00 and 12:20 was this:

(the server the script tried to write a file to was down at the time so the script failed)