Our integration is built using the REST API. We have one client who's Campaigns are not appearing. The Campaign Is Requested Trigger is configured properly and the campaigns are active. We're only seeing this happen with this one client account, but for this account no campaigns are showing. Are there additional settings that should be checked?
Are you getting a paging token in the response? It's very possible that the campaign just isn't in the first page of results.
Does the client have workspaces and partitions enabled for their subscription? If so, your API user may be missing an appropriate role in the desired workspace. Do you have any of the filter params set?