Integration error between AEM and Adobe Events - cannot be cast to java.util.Vector

[CrisBlacks]

Hi, I am trying to integrate my AEM on premise (6.4.8.4) with Adobe Events (cloud). I followed this guide: https://developer.adobe.com/events/docs/guides/using/aem/aem_on_premise_install_6.4/

I only have the default events (created with the bundle installation), but the event instances fail to load properly. When starting the author for each of the 5 default events I get this error:

24.03.2022 17:16:21.535 *INFO* [FelixStartLevel] com.day.cq.dam.eventproxy Service [com.day.cq.dam.eventproxy.service.mapping.OsgiXdmEventMappingConfigurationImpl.cbe7c66d-0be7-406e-b879-2f50a448e8be,7742, [com.day.cq.dam.eventproxy.service.mapping.OsgiXdmEventMappingConfiguration]] ServiceEvent REGISTERED
24.03.2022 17:16:21.536 *INFO* [FelixStartLevel] com.day.cq.dam.eventproxy.service.impl.CsmRegistrationImpl Adding an Adobe IO Events OsgiXdmEventMappingConfiguration: OsgiXdmEventMappingConfigurationImpl{ EventCode='page_unpublished', EventLabel='Page Unpublished Event', osgiJcrPathFilter='/content/', osgiTopic='com/day/cq/replication', osgiFilter='(type=DEACTIVATE)', osgiEventHandlerClassName='com.day.cq.dam.eventproxy.service.impl.listener.PageReplicationEventHandler', adobeIoXdmEventClassName='com.adobe.xdm.event.AemPageUnpublishedEvent'} ...
24.03.2022 17:16:21.536 *INFO* [FelixStartLevel] com.day.cq.dam.eventproxy.service.impl.CsmRegistrationImpl Adding Adobe IO Events metadata associated with OsgiXdmEventMappingConfigurationImpl{ EventCode='page_unpublished', EventLabel='Page Unpublished Event', osgiJcrPathFilter='/content/', osgiTopic='com/day/cq/replication', osgiFilter='(type=DEACTIVATE)', osgiEventHandlerClassName='com.day.cq.dam.eventproxy.service.impl.listener.PageReplicationEventHandler', adobeIoXdmEventClassName='com.adobe.xdm.event.AemPageUnpublishedEvent'}
24.03.2022 17:16:21.536 *INFO* [FelixStartLevel] com.day.cq.dam.eventproxy.service.impl.CsmRegistrationImpl Http POST-ing Adobe I/O Events CSM with Metadata EventMetadataDTO{eventCode='page_unpublished', eventType='null', provider='AEM-BB3412531234459F0A490D45@AdobeOrg_localhost', description='Page Unpublished Event from AEM-BB3412351234459F0A490D45@AdobeOrg_localhost', label='Page Unpublished Event', topicName='null'}
24.03.2022 17:16:21.540 *ERROR* [FelixStartLevel] com.day.cq.dam.eventproxy.service.impl.CsmRegistrationImpl The provided OsgiXdmEventMappingConfiguration was invalid, hence dismissed.
java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.util.Vector
	at com.day.cq.dam.eventproxy.service.impl.AdobeIoAuthProxyImpl.getOrganizationId(AdobeIoAuthProxyImpl.java:155) [com.day.cq.dam.eventproxy:6.4.190]
	at com.day.cq.dam.eventproxy.service.impl.AdobeIoAuthProxyImpl.getAdobeIoOAuthHeaders(AdobeIoAuthProxyImpl.java:146) [com.day.cq.dam.eventproxy:6.4.190]
	at com.day.cq.dam.eventproxy.service.impl.CsmRegistrationImpl.postEventMetaData(CsmRegistrationImpl.java:318) [com.day.cq.dam.eventproxy:6.4.190]
	at com.day.cq.dam.eventproxy.service.impl.CsmRegistrationImpl.addEventMetadata(CsmRegistrationImpl.java:290) [com.day.cq.dam.eventproxy:6.4.190]
	at com.day.cq.dam.eventproxy.service.impl.CsmRegistrationImpl.bindOsgiXdmEventMappingConfiguration(CsmRegistrationImpl.java:133) [com.day.cq.dam.eventproxy:6.4.190]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)

Also trying on Sling Health Check to check the status of csm-events I get a Critical error also of type Vector casting.
Trying to perform manual actions on the Author to trigger the events, are not sent to Adobe Events. Calling the Journaling API I get code 204 (no content).

I also attach the event configuration related to this specific log

Does anyone know how to solve this?