Hi Eoin,
To check the website address on Office 365 portal, take the following steps:
1. On the Admin page, in the left pane, under Management, click Domains.
2. Beside Change address, to check if the address is default address like yourdomain.sharepoint.com. If not, change it back to default address.
3. Wait for a while. After the original A record disappears under DNS Manager, you can start to add the new A record again.
Thanks,
Ida Qiu
To check the website address on Office 365 portal, take the following steps:
1. On the Admin page, in the left pane, under Management, click Domains.
2. Beside Change address, to check if the address is default address like yourdomain.sharepoint.com. If not, change it back to default address.
3. Wait for a while. After the original A record disappears under DNS Manager, you can start to add the new A record again.
Thanks,
Ida Qiu