The lastRun field in the response schema of /beta/campaigns/{id}/reports is being deprecated in favor a new field called lastRunAt. This change is being made to ensure our APIs better align to our API standards when representing dates. lastRun is represented as a Unix epoch timestamp, which is not consistent with the rest of our date fields. lastRunAt will use the standard date-time format.
If you are using /beta/campaigns/{id}/reports and rely on the lastRun field being present, then please update your code to use the new lastRunAt field which is currently available.
The lastRun field will be removed from API responses two weeks from this announcement, which is September 5th of 2022.