What you were expecting to happen, and what actually happened?
I was expecting to receive bonus Guild Chest keys in the mail from a guildmate’s purchase. I did not receive any bonus keys from their purchase.
What are the steps to make it happen again?
Unsure. Purchase Guild Chest keys and see if all your guildmates receive the bonus keys from your purchase.
Do you have any screenshots or video you want to share with us so we can see the problem? Attach them to your post!
Unfortunately not. It’s hard to take a picture of you not receiving something. 
This is actually the second week in a row this has happened from the same member (making the purchase) but other members’ purchases deliver the keys just fine. I don’t know if that is just a coincidence or if the issue is related to their account. Also not sure if it’s related but this never happened on the old servers (that I’m aware of).
A support ticket was already opened and resolved for last week’s issue and I’ve opened a new one for this week’s issue but I wanted to post here in case other guilds have been experiencing this, too.