ODBC DSN cannot find database

I have started mongosqld with --sampleNamespaces mydb.mycollection and I see this message which seems to indicate that it’s recognized -

I SCHEMA [sampler] mapped schema for 1 namespace: “mydb” (1): [“mycollection”]

but when I try to create a system DSN with database “mydb”, I get an error:

handshake error: ERROR 1043 (08S01): error using database mydb: ERROR 1049 (42000): Unknown database ‘mydb’.

If I leave the database blank when creating the DSN, it creates the DSN but when I try to use it in Power BI, I see only “INFORMATION_SCHEMA” and “mysql” under the DSN and not “mydb”.

Thanks in anticipation for any help.