Did you click the "X" icon on a notification and now the notifications are no longer displaying? If that's the case please follow the steps below to fix.
How to make notifications reappear on Desktop Chrome
In the Chrome web browser please click the three dots on the top right.
Next, click on "More Tools" and "Developer Tools"
Then, click on "Application" and "Local Storage" in the left menu.
Finally, right click on the entries under "Local Storage" and click "Clear"
Refresh your browser and that should do it.