Found a solution to my problems with Micro.blog and Sunlit apps not discovering my XML-RPC endpoint.
All connections to the xmlrpc.php file were being blocked. I read a few posts when trying to find a solution that the xmlrpc.php file is a big target for brute force attacks on websites. So maybe my host had pushed out an update to block access to any xmlrpc.php files.
To fix this problem, I added the following code to my .htacces file and now everything connects without problem.
<FilesMatch "xmlrpc\.php$"> Allow from all </FilesMatch>
It would be nice if I could ‘Allow from’ Micro.blog and Sunlit instead of ‘All’ but this is something I can tweak at a future date.
Right now I’m just happy everything is working again correctly.