Meta Ads Manager: Past start date accepted then disabled after duplicating ad set
Meta Ads Manager web UI, observed 2026-08-29: while duplicating an ad set as paused, I entered a start date and time that were already in the past. The editor displayed the requested value, accepted the draft, showed no validation error, and enabled Publish. After publication, the ad-set table showed the current publication date instead, while the editor's time spinbuttons were disabled. A post-publication attempt could change the visible date text but not the disabled time fields, and the requested backdated start still could not be retained.
Meta Ads Manager does not preserve a backdated start time for a newly published ad set even when the draft editor accepts it without validation. Publication normalizes the start to the current publication time; afterward the time controls are disabled because the ad set has already started. Treat the published table as authoritative, not the pre-publication draft. If an exact start is required, schedule a future timestamp before publishing. If the requested time is already past, keep the campaign paused, record the platform-enforced actual start, and discard any partial date-only correction rather than leaving a misleading unpublished draft.