Hi baker999855,
I can confirm that my testings all have running with the newest WSUS updates - so Windows 10 Cumulative Updates for march are installed on my master Win 10 20H2.
If this problem is production fencing for you, you can create as a workaround the "x64" folder under the "wdav-update" shared folder and copy the newest mpam-fe.exe under this "x64" folder.
With temporarily deactivating the local GPO on your master template for "Define file share for security intelligence updates" and only activating the local GPO "Define file share for security intelligence updates" all pooled VDI clients will download the mpam-fe.exe file from the "x64" folder from the share and are extracting it by themselves for updating Windows Defender.
That's why I am using the long term script of JesseEsquivel for downloading the security intelligence updates. The script is considering this circumstance and will create the GUID folder for the extracted delta signature updates and is copying the newest mpam-fe.exe to a "x64" subfolder on the "wdav-update" share.
Best,
Daniel