I'm having the same issue. I tried combining DATEDIFF and TIMEDIFF like:
DATEDIFF(col1,col2)*24*60 + TIME_TO_SEC(TIMEDIFF(col1,col2))*60
but it still isn't working with dates that are less than 24 hours difference, but fall on different calendar days. i.e 10/09/2017 23:00:00 and 10/10/2017 03:00:00. This should give an answer of 240 minutes, but instead I'm getting 1,680 minutes.
I think I'll have to do these calculations on the backend because Domo just doesn't seem to have the ability to easily do a timestamp difference, but someone please correct me if I'm wrong.
This code should work for difference between timestamp longer than a day.
If you had Start Date of 19-Sep-18 2:31:25 and End Date of 20-Sep-18 3:15:22. The time differnce in minutes should be 1483.57( 57 is the seconds).
((DATEDIFF(`end date`,`start date`)*1440)+(HOUR(TIMEDIFF(`end date`,`start date`))*60)+(MINUTE(TIMEDIFF(`end date`,`start date`)))+((SECOND(TIMEDIFF(`end date`,`start date`)))/100))