Apple voip notification expiration doesn't work

I send voip notifications using curl to apns server. I use the following script:
Code Block
curl -v \
--header "apns-topic: **.voip" \
--header "apns-priority: 10" \
--header "apns-push-type: voip" \
--header "apns-expiration: 0" \
--cert-type P12 --cert *** \
--data '{}' \
--http2 \
https://${APNS_HOST_NAME}/3/device/${DEVICE_TOKEN}

I disable wifi and cellular data for 1 min and send voip notication. apns-expiration header works fine when APNS_HOST_NAME is api.sandbox.push.apple.com - I don't receive voip notification. But when APNS_HOST_NAME is api.push.apple.com - I receive voip notification when I enable wifi back after 1 min, 1.5 min ...
I'm not sure what is wrong and what causes such difference in sandbox and production modes. Does anyone know how to solve this?

The issue is fixed?

Apple voip notification expiration doesn't work
 
 
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