Raised a ticket here REALMS-11622

Then spoke to Ronalyn at Microsoft Support

They confirmed I have an active Java Minecraft Realms You + 10 Friends Subscription Server 1 in my account.

They raised Microsoft Support ticket 7010823576

Requested I raise a ticket here as it's a Minecraft Account Issue and MS cannot resolve this issue

Ideal solution. 
I would like to have "Jasper's Awesome Realm" reactivated with the subscriptions I have paid for. I do not want to create a new realm.

I have fully updated my PC

I have reinstalled the Minecraft launcher and Java Edition

I can see this is an issue on the MC Account website, in Java and in the launcher.

This is apparently not a Microsoft Support issue.