Frustrating. Reading through this thread a smile grew on my face as I realised I had found the resolution to my issues.
Alas not. I have exactly the same problem as those mentioned here, but not the same reason. I have not changed instance names etc. Indeed this has occured on a deployment that has been working for months before. I left to go on paternity leave for 2 weeks, returned to find that I could not amend any subscriptions, and whilst the job in SA appeared to be running properly, no reports were being emailed out.
I get the same message as others here. I did check, for happenstance, to see if my triggers had changed, but mine do reference the correct locations etc.
I don't hold out much hope, but if anyone can help with that i'd be eternally greatful.