Windows 10 1709 systems stopped updating via WUSS after March 2019 updates

Hello guys,
what’s a matter,
There is a problem which I am facing so much nowadays especially the last few months
I noticed all our 1709 system stopped receiving Windows Updates from our WSUS server after the March updates were applied.
Their build numbers show as 1629.1029 which is a March 2019 build. They are not receiving any April 2019 cumulative updates.
There is no error. Both the WSUS server console and the local check for updates GUI show up to date when checking for updates and the last status report date and time are current.
Windows 10 1803 systems are fully up to date including April 2019 cumulative updates, so I know the WSUS server is successfully synchronizing current updates for other versions of Windows 10.
What could be causing Windows 10 1709 systems not to get cumulative updates, yet 1803 updates fine?
Any suggestions appreciated?
Thanks a lot in advance.

Hello @Davies

Would you share the screenshot of the error message, meanwhile
you can use the following link to solve the problem it is supported by Microsoft Team.