I'm sorry if this isn't the correct way to report a bug, but I couldn't find another way to do it. I also appoligize if this has already been brought to your attention.
I'm running Orion 3.5.1 with NTA 3. I had to update a node because of an IP address change, and it just happened to be one of my core routers monitored in NTA. Orion took the change in stride, and I didn't have to update my maps or anything, but my application monitoring charts immediately gave a no data error. When I drilled into my NTA settings, I saw two entries for the router, one monitored and one not. No about of switching between the two yielded desirable result, so I "un-monitored" them both and applyed the change. I went back in and there was only one entry. When I selected it, my charts started working again. Nearest I can figure out, NTA was trying to poll the old IP address, so Orion must not have updated it. I allowed a 36-hour window between changing the node and investigating the charts, so it's not just a replication issue.