Gonna submit another post in a minute - we're testing a little more.
Well, after vacation, back in office, talked to my peers and decided to test the following:
Our WSUS in our domain feeds our clients select updates: Only critical updates and patches, no snazzy **** we don't need. Philosofized over this a bit and thought along the lines of 'what if one or another patch included something in preparation for upgrading
from 1809 to 2004. We have had instances where MS would push out patches in preparartion for something to follow at a later stage.'
So we already have our test OU in Active Directory where we unlinked all GPOs that could enstrangle a Win10 client in any way. Starting out with the client at Win10 1809, it gets tons of updates: Cumulative, Servicings Stacks, and [watch:] Feature Update
to Win10 1909, followed by Feature update to Win10 1903 (!) and is now spinning at 78% since 80 minutes and seems stuck once more.
Will post a follow up when I get there.
Update: 7 hours later winver shows Win10 1903 build 18362.1082. Rebooting and checking for updates yet again, gives me 'You're up to date'.
Gonna recheck for updates on a daily basis until I finally (hopefully) have a 2004 machine.
For heaven's sake MS get your f*cken act together!!!!!oneeleven