Install Wireshark on Orion server (and additional poller if you point some netflow there as well), and verify you are still receiving flows from those device. Using filters like ip.src==AAA.BBB.CCC.DDD && (cflow || upd.port==2055 || udp.port == 6343 || udp.port==9996) to go find out if you are receiving flows from each device.
If don't you see flows in Wireshark check your devices (configuration changes that disable netflow as sideeffect, e.g. cef) and network (firewalls, routing). If you see flows in Wireshark, but not in NTA, go to NetFlow sources > Manage sources > uncheck the checkbox next to not working flow source > submit > go back > check that checkbox again > submit. If that doesn't help, open a support ticket with SolarWinds.