Latest Windows 10 (1803) has deactivated my windows 10

I am on my third version of W10 Pro (1803) upgraded free years ago from windows 8.1 pro. Today assuming after doing windows update my PC says its now not activated. Going to activation screen and reentering my key (from SIW) it says I havent got a digital license and would I like to buy one from the windows store. And its seems to have changed from win10pro to win 10 enterprise for some strange reason because I also tried the default key which showed up in SIW. Is this a microsoft server issue and should I just leave it a few days. Of course phoning the microsoft 0344 number you just get options that are not relevant and cannot find a person! Obviously putting my win 8.1 pro key in does not work. Any ideas or do I have to reimage!

See here MSFT acknowledges some Win10 Pro licenses being mistakenly deactivated - Windows 10 Forums

@Mike8, the activation server now appear to have been fixed. You can now re-activate your Pro by using the command slmgr /ato in a command prompt.

Bree said:

I can now successfully run slmgr /ato on my test machine, previously it failed to activate.

MSFT acknowledges some Win10 Pro licenses being mistakenly deactivated - Page 4 - Windows 10 Forums

doesnt work for me yet, but a microsoft techy did acknowledge the issue and wait a couple of days but hed did remotely get my w10 pro version back.

tried it again, not activated :)

@Mike8

Try it now, it should work.

Yes it has worked now. Thanks for the prompt help on this forum.
Incidentially I have found a better number for direct m$ support 0800 026 0329.

LIkewise, the update de-activated my copy of Windows 10..

"Troubleshoot" resolved it but my confidence that it won't happen again is significantly reduced.

ShowKeyPlus indicated the original key was present but I now have a "digital key".