Hello,
We had the exact same problem with our new 11d install (the old 8.6 was running fine...)
It seems that the Domino agent is buggy (the symantec support people told me about a "know problem")
I haven't seen anything about that on the latest (7071) BE release notes, so for know i'm staying on 6235...
But the main issue is that the communication problem between the BE server and the Domino agent lead the backup jobs to WAIT.... not to fail... so, no error message, no way to bypass the server with the buggy agent to continue the jobs... and restarting every BE Agent on all of my Domino servers every day is not a realistic solution....
So, we are waiting for a fix from Symantec (at least a bit of communication will be appreciated...)