VMware GRT enabled job stuck at backing up system state

Hello,

We are having problems with the GRT-enabled Backup Job of our VMWare environment. We have two different jobs to back up our virtual machines. One with GRT disabled works just fine but the other one with GRT enabled get stuck at different server always at backing up the system state. 

Our virtual enviroment ist running at vmware 5.1

Thanks for any help!