Can't cancel or suspend a BPM process that's in progress

Hello,

I'm getting a strange error when trying to cancel or suspend any of the running BPM processes, from the NWA.

I first select any of the running processes, and then, in the actions dropdown I select either "cancel" or "suspend". This causes the following error:

If I go to "see Logs", I only get this error:

Retrieval of User data in 'Manage Process' has failed in Suspend method.Contact Support[Ljava.lang.StackTraceElement;@76ca171f

Does anyone have any idea what could be causing this? We are on 7.31, in a clustered environment with 2 nodes.

Thanks!