After researching the issue, having the same problem, I found the culprit blocker in Remote Desktop shield settings, there you can see a logging page with details of every block result and by clicking the settings cog on the right you can allow brute force attack option by unticking it but to still keep safe, at the bottom select block all connections but only allow following ip addresses, add the needed addresses, select Allow.
that worked for me and probably work for you too.