Hi Fabio
Can you elaborate how the cluster looks like? The global variables are cached in the Java Server for better access and are transferred to various app server via JMS. If your JMS messages are stuck it may be a reason for the variables not reflecting on the other app server.
Best option may be to restart the cluster. Or better still if you can use shared properties of MII 12.2 and not global variables.
Regards
Partha