google cloud messaging - Android GCMNetworkManager not executing while device idle -

i've used gcmnetworkmanager schedule service runs every minute. it's working fine while device active, once phone goes idle, i'm getting mixed results. (i tested 3 devices today service running whole day, writes date/time file).

galaxy s6, task fired around 4 hours, stopped until turned screen on. htc 1 m9, task fired on , off (but not consistently) around 3 hours, stopped until turned screen on. htc 1 m7, task stopped firing pretty after phone went idle , never ran again day.

i want service run while idle, doing wrong?

    long periodsecs = 60l; // task should executed every 1 minute     long flexsecs = 30l; // task can run -30 seconds scheduled time     string tag = "task_scan";      periodictask periodic = new periodictask.builder()             .setservice(myservice.class)             .setperiod(periodsecs)             .setflex(flexsecs)             .settag(tag)             .setpersisted(true)             .setrequirednetwork(task.network_state_connected)             .setrequirescharging(false)             .setupdatecurrent(true)             .build();      mgcmnetworkmanager.schedule(periodic);