Troubleshooting user who changed email via wordpress sso, not getting notifications since then

Hello everyone! I am investigating an odd problem on my site with one particular user. I will be setting up some test accounts to try to replicate it, but in the meantime I was hoping for some pointers.

The issue is that a user has changed their email address via wordpress. I can see the new email address is in both places. The user is activated and user prefs are set up to receive notifications (see below).

Despite this, unfortunately, the user stopped getting email notifications entirely on the day they changed their email address. I can verify this both in mandrill and in discourse admin, sent email list.

The main issue is a specific PM that has important info that this user needs to be getting notified about. I noticed that I can’t see and set the user’s notification level for specific messages or topics? Is there a way to see it?