Family group chat iMessage missing randomly
All my family members have iPhone 6/6S and we use iMessage to communicate via a group chat. All our iMessage are properly set up on the phone because we can send messages to each other one-to-one with no problems.
However when I send a message to the family group, some members don't get the message while others do. Sometimes everybody will get the message.
The recipients are definitely correct -- they all appear blue and I verified the phone numbers and email addresses. And they ALL CAN get messages I send to the group some of the time.
There is no indicator whether my message has been delivered or read in the group chat. I don't know who has got my message and who hasn't unless I ask them to check their phone.
This seems to me to be a very serious issue -- none of the other messaging platforms has this problem (Facebook, WeChat, LINE, What's App, SMS) and this is quite a serious bug if you're making a messaging platform!! Any advice how I could debug or workaround this would be most appreciated. Thanks.