Statistics collection of random node fails when large number if switches disconnects from controller

When large number of switches (>32) disconnects from the controller and connects back, statistics collection of random nodes fails. This issue can be recreated using the following steps. You might have to try more then one attempt to recreate it.

1) Start controller and install dl-openflowplugin-flow-services-ui feature
2) Connect mininet to the controller
sudo mn --controller=remote,ip=<controller-IP> --topo tree,6 --switch ovsk,protocols=OpenFlow13

Wait until all stats are collected.Stats collection works fine for all the nodes.

3) Disconnect mininet from controller

4) Again start and connect mininet to controller
sudo mn --controller=remote,ip=<controller-IP> --topo tree,6

Statistics of few nodes will be missing.