When Ancestry introduced the new messaging system, I was annoyed that I no longer received email notifications about incoming messages. I contacted Ancestry, and they explained how to overcome that problem:
As part of the new message system, we are attempting to cut down on the emails we send to our members. The sheer number we are sending in some cases is causing email domains to pre-filter our important emails out along with promotional [spam!] and this is causing considerable hardship.
We have changed the process, so that we only send out one email for multiple replies, and we only send an email when you have been logged out completely from our site for a while. This way, you are not getting emails while you are working, but can still view your new messages within your account as they come in.
If you just close your browser instead of logging completely out, the emails may not send at all, because your browser's active login cookie tells our site you are still signed in. To prevent this, simply click on your name or username at the top right and choose Sign Out.
Once you have been signed out for a little while, notifications will start coming through email again.
This works! I now log out each time I use the site, and I'm getting notifications again. But many people don't know about this, and our messages are just sitting in their inbox at Ancestry.
There are, of course, many reasons why someone might not reply to your message - but please share Ancestry's 'log out' explanation with your friends and family history groups.
See also the excellent advice in this post by Margaret O'Brien: In-Depth Guide - Chapter 9 - Send Ancestry Messages that get Replies.
Note that you have until 31st August 2020 to download and save your messages from Ancestry's old system.

This post first appeared on https://genie-leftovers.blogspot.com/2020/07/why-you-dont-get-replies-from-ancestry.html.