Cannot connect from my personal Liquid report to the database

Anonymous Is the issue maybe the authentication type? See the solved thread here:

https://community.powerbi.com/t5/Desktop/DataSource-Error-Microsoft-SQL-A-connection-was-successfully/td-p/720906

Other sources of potential information:

https://techcommunity.microsoft.com/t5/sql-server-support/a-connection-was-successfully-established-with-the-server-but/ba-p/318883

https://stackoverflow.com/questions/9890971/sql-server-a-connection-was-successfully-established-with-server-existing-c

Those are not specific to Power BI. 

If all else failes, you could check the Issues forum here:

https://community.powerbi.com/t5/Issues/idb-p/Issues

And if it is not there, then you could post it.

If you have Pro account you could try to open a support ticket. If you have a Pro account it is free. Go to https://support.powerbi.com. Scroll down and click "CREATE SUPPORT TICKET".