hi, in some critical cases we want to monitor the time taken to finish a task. the team has been asked to update the fields "Start date & time" and "End date & time". Is there any way the time taken (in hours) can be calculated and automatically updated in the field "Time tracking". if not in "Time tracking", which other field can be used to update the time taken from the difference between end date time & start date time. As of now I'm not getting the option to select the field "Time tracking", instead I have selected original estimate. but I want time "Time spent" in "Time tracking" field to be updated with the hours.
I tried setting up an automation, but getting the below error with it:

and this is the automation workflow. I have added the smart

value {{issue.customfield_10134.diff(issue.customfield_10133).hours}}h