our tech. support has experienced this anomaly too and the root cause is most likely the way those vlans were configured on the device. Copying one vlan from another didn't put it into vlan membership table as it should.
This should happen all automatically on the side of the switch so not sure what other workaround can be provided by SolarWinds.
What exactly does this mean?
"Copying one vlan from another didn't put it into vlan membership table"
I have the same problem on my 2960's. These are access ports, so I can't dedicate a port on each switch. I tried to make the adjustment as in this Thwack, with no luck. I tested and assigning a port on the 2960 worked, but it is not practical.