Update 4/18:

Known issues in this update

Symptom Workaround
After installing the March 13, 2018 or later Cumulative Update for Windows 10 version 1607, only the latest Windows 10 feature update is returned as applicable. This prevents the deployment of previously released feature updates using ConfigMgr (current branch) and Windows 10 servicing plans. Decline all feature updates on the WSUS Server(s) except for the one that you want to deploy using ConfigMgr. Run another software update scan cycle from the ConfigMgr control panel (or wait until the client devices perform their next scan).

Microsoft is working on a resolution and will provide an update in an upcoming release.