Chimes are getting delayed

I am a pro user of Cyanax Hourly Chime,
Using Vivo v9 handset.
My chimes are getting delayed for about 2 to 3 minutes when my display is off. Sometimes are in que and deliver as soon as my display turns awake.
Even after setting chimes as alarm clock in advanced settings, no use. Alarm clock icon is not displaying in status bar as mentioned in these settings.
Kindly help.

Hi. This is typical for battery saving options. Please go to device battery settings and check if there are any additional settings you can turn off.

You can also experiment with app “Advanced” settings.

Unfortunately on Android 5+ it is highly recommended to “set chimes as alarm clock” - otherwise device might postpone them. Only alarms are guaranteed to run on time - although on some devices like Xiaomi or Huawei there is problem with that if you don’t turn off additional Xioami or Huawei battery optimizations for this app.