We see that stacked bars are not displayed correctly with data coming from Flux datasource. We tested with Grafana 5.2.1 and the latest 5.3.2 - the pictures are the same.
#datatype,string,long,string,dateTime:RFC3339,long
#group,false,false,true,false,false
#default,_result,,,,
,result,table,process_name,_time,_value
,,0,dtquery,2018-10-28T06:00:00Z,2
,,0,dtquery,2018-10-28T07:45:00Z,2
,,0,dtquery,2018-10-28T15:45:00Z,1
,,0,dtquery,2018-10-28T16:00:00Z,1
,,1,objcontrolsvc,2018-10-28T08:00:00Z,1
,,1,objcontrolsvc,2018-10-28T08:15:00Z,1
,,2,storageserver,2018-10-28T08:00:00Z,2
,,2,storageserver,2018-10-28T09:15:00Z,2
,,2,storageserver,2018-10-28T13:45:00Z,2
,,2,storageserver,2018-10-28T14:15:00Z,2
,,2,storageserver,2018-10-28T16:45:00Z,2
,,2,storageserver,2018-10-28T18:45:00Z,3
,,2,storageserver,2018-10-28T19:00:00Z,1
,,2,storageserver,2018-10-28T20:00:00Z,2
,,2,storageserver,2018-10-28T20:15:00Z,2
,,2,storageserver,2018-10-28T20:30:00Z,2
,,2,storageserver,2018-10-28T20:45:00Z,1
,,2,storageserver,2018-10-28T21:45:00Z,1
,,2,storageserver,2018-10-28T22:00:00Z,1
,,2,storageserver,2018-10-28T22:30:00Z,2
,,2,storageserver,2018-10-28T23:30:00Z,2
,,2,storageserver,2018-10-29T00:45:00Z,2
#datatype,string,long,string,dateTime:RFC3339,long
#group,false,false,true,false,false
#default,_result,,,,
,result,table,process_name,_time,_value
,,0,storageserver,2018-10-29T00:45:00Z,2