Windows 10 1709 x64
CU May 19th 4505062 and CSU June 11th KB4503284 were installed last week. The option to Switch User is now missing from the user menu in Start.
A gpresult report does not show "Hide Entry Points for Fast User Switching" as being confirmed on the client and so the patch seems to have switched this to disabled by default.
Setting "Hide Entry Points for Fast User Switching" in local gpedit.msc brings the option back. The option says "Switch Account" now.