You are unable to see the update notification of an KR, although you know progress has been made on that KR.
The affected OKR has been cloned to another session.
If you make an update to an OKR in a session, then you are able to see the update notification up in right. Here the screenshot:
If you clone the updated OKR to another session and open it, then you will see the following screen.
As you see the update comment is missing because you have duplicated the affected OKR, and the second one is recognized as a new one from Gtmhub. It is really never been updated and that is the reason, why you are not able to see the update notification.
You can find the update notification in the primary KR created in the account.
Go to the "Hub" view
Search for a KR with the same name as the cloned one