inconsistency between couchdb active_tasks and /pools/default/tasks

Sometimes UI displays indexer tasks while _active_tasks on port 8092 returns an empty array:

curl -u Administrator:password http://10.2.2.31:8091/pools/default/tasks
[

{"type":"rebalance","status":"notRunning"}

,

{"type":"indexer","recommendedRefreshPeriod":2.0,"status":"running","bucket":"default","designDocument":"_design/dev_ddoc2","changesDone":19403,"totalChanges":36471,"progress":53}

,

{"type":"indexer","recommendedRefreshPeriod":2.0,"status":"running","bucket":"default","designDocument":"_design/dev_ddoc1","changesDone":48055,"totalChanges":103174,"progress":46}

]

curl 10.2.2.31:8092/_active_tasks
[]