The campaign number present yesterday is missing/different in Email Threat Analytics today.
Email Security.cloud
The campaign number is auto-generated for every new daily report.
An active long-running campaign should still be present the next day, but would have to be identified by some means other than the campaign number, which would likely be different. Clients are advised to review the indicators such as : subject, source IPs, etc. of the previously identified campaign and ensure to find a matching campaign if it hasn't been adjusted.
Note: "Campaign ID" is recomputed or reevaluated on a daily basis. A campaign is just a collection of emails likely belonging to the same or related attacks calculated over a moving window of data over time. Therefore, what is presented is a daily snapshot based on that period for the current set of data available.