Ok,
One i have both the Java edition and the windows launchers installed, and have been playing with my friends on their bedrock realm via windows edition for weeks now with no issues.
However yesterday i was disconnected from the realm and unable to see neither the realm nor my online friends in the menu.
I followed the usual trouble shooting, restarted the game, my pc and even reinstalled both the launchers. only now when i open up the windows ver. to go into realms the sign in option won't let me sign in, only giving me the 'Cauldron' error message, I followed the online trouble shooting and no resolution came from that. Tried re installing the launchers again bit nothing the same error.
To note i can still see the realm in the menu before launching the game and am able to get on just fine with the java version.
To note as well my friend is also accessing the realm in the same way as me via windows launcher and has not experienced any issues, and the owner of the realm has sent me additional invites that come through but still nothing.

I have already asked for advice from the Minecraft help team and followed their suggestions but still no luck.

I have ruled out internet connectivity issues as i have attempted it across three separate networks.

I have reinstalled the launcher multiple times, checked my permissions and firewall to make sure I don't have anything blocked, and have attempted completely logging out of my Microsoft account and then restarting the game and re-logging in, but still no result. 

Any advice would be appreciated.