Default Email Signature Not Saving

Help!!

I have multiple email accounts in Outlook 365.

When I select the default signature for Account A for new messages and replies/forward and click OK I can the create a new email using that signature.

However my default signature for Account B changes to "none".

I then reselect the default signature for Account B and click OK and I can then create new emails using that signature.

But, the default signature for Account A has changed to "none".

Each time I use a different email account I have to reselect the email signature before I create or reply to an email in that email account.

This behaviour, as far as I can determine, has only commenced since the look changed and the option was available to sync signatures across devices.

I'm currently on:

Looking at the "What's New" information, there was an update on November 6, 2020, Version 2012 (Build 13430.20000).

That update is when I started having issues with my email signatures!

The update notes included:

Outlook

Same signature on all devices

Your signature is stored in the cloud. Create it once and use it everywhere you use Outlook for Windows.

I think there is an issue in that my signatures are not being stored and hence I'm having to apply them each time I use a different email address.

Anyone have any ideas as to how to resolve this issue without creating a new profile?