The reporting tool will work.
You can also write a SQL query.
Note that AH is for history --- EH would be used for currently running jobs and has different columns
try something similar to -- adjust for your exact AE version and your DB (Oracle or MSSQL)
Another option if the ah_runtime is not populating or your object type, calculate the difference between ah_timestamp2 and ah_timestamp4.
select Oh_idnr, oh_client, oh_name, convert(varchar(25), ah_timestamp2,120) , convert(varchar(25), ah_timestamp4,120),
ah_runtime, oh_ert
from oh, ah where ah_oh_idnr = OH_idnr
where ah_runtime > oh_ert
********** pick selection criteria, by otype, date range, status, name......... ***************
and oh_client = 1000 ------------------restrict to a single client
and ah_runtime > oh_ert * 2----------------------------runtime is at least twice ert
and ah.ah_timestamp4 is not null -------------------------needs to have completed to be considered
and oh_otype = 'JOBS' ----------------limit to JOBS only
and convert(varchar(4), ah_timestamp4,112) = '2018'-----only use current year
and ah_status = 1900 ------------------- only successful jobs
order by oh_client, oh_name ...................
Pete Wirfs and others have postings that group or average this type of value
--- makes it easier to focus on those that run long most often