Hello!
This on the surface looks to be a potential timing issue, if it only occurs intermittently. Will you share the method you are using to implement the ECID service? Is it through launch or javascript?
If you are doing it manually through javascript will you confirm whether you are setting the 'disableThirdPartyCookies' flag on the first instantiation of ECID service via the getInstance Method on the page?
for example I would expect it to include the disableThirdPartyCookies flag there:
var visitor = Visitor.getInstance("INSERT-MARKETING-CLOUD-ORGANIZATION-ID-HERE", {
trackingServer: "INSERT-TRACKING-SERVER-HERE", // same as s.trackingServer
trackingServerSecure: "INSERT-SECURE-TRACKING-SERVER-HERE",
marketingCloudServer: "INSERT-TRACKING-SERVER-HERE",
marketingCloudServerSecure: "INSERT-SECURE-TRACKING-SERVER-HERE",
disableThirdPartyCookies: true
});
If you can share steps to reproduce here, that would also be helpful. Otherwise, please create a ticket with customer care.
Best regards,
Garrett