One of my managers have this problem of not receiving an email notification when a new entry is made in one of the sites on SharePoint, although he receives email from other groups and sites entries. Any idea on how can I fix this issue?
Where do you create the alert? Do you create alert on a library or list?
Refer to the following article about users don't receive SharePoint Online alert notifications:
To receive the alert the person must be at least viewers of the site, check if this user is in the permission structure of the site/list/library
Try this to troubleshoot the issue:
And check "Immediate Alerts" timer job