From the error you posted it seems that the security policy was not changed correctly.
The change in the policy will not be available when moving your app to the cloud.
What you could do is in the settings disable the emulate cloud security and see if this fixes the issue. If so then fix the security policy for the used modeler and re-enable the emulate cloud security option to see that this fixed the issue.
If so then file a ticket with Mendix support to request your policy change to be added to your environment.
Thanks Erwin, for your help. After disabling the emulate cloud security it seemed to fix this error.
Afterwards we found that adding the following permissions to modeler 6.10.13 works:
permission javax.management.MBeanPermission "*", "*";
permission javax.management.MBeanPermission "com.amazonaws.metrics.MetricAdmin#-[com.amazonaws.management:type=AwsSdkMetrics]", "registerMBean";
permission javax.management.MBeanServerPermission "*";
permission javax.management.MBeanServerPermission "createMBeanServer";
permission javax.management.MBeanServerPermission "findMBeanServer";
permission javax.management.MBeanTrustPermission "*";
permission javax.management.MBeanTrustPermission "register";
However, we found a new error, where there is a conflict between the same libraries. We are now trying to figure that one out!