Usually, Windows Server Update Services (WSUS) will automatic syn all the latest update to itself after Microsoft release. For some reason, some updates are not available in your WSUS. It seems that the latest Update you are finding for has not been added to the WSUS channel. It may be added in the near future.
For reference, you can check KB4489899 to see if an update has been posted to the WSUS channel: Description of Software Update Services and Windows Server Update Services changes in content for 2019
If the update you need has not been posted to WSUS channel. For this time, you may need to be added manually.
Let see how to add an update manually.
Open Windows Server Update Services, Navigate to Updates section.
On the right panel click Import Updates… you will be redirected to the Microsoft Update Catalog.
Navigate to the Search box… find the update you need. You can also add multiple updates to the basket.
click view basket
Finally, click Import, wating for a while the updates will be added to your WSUS database.
Back to the main windows, click on the search box to verify the update added.
Thank for reading, hope it help.