Empty v$asm_diskgroup with sqlplus

I have an Oracle Database instance installed under an OL7. It is a 12c2. Oracle GI also installed and my database has some files stored in ASM. I am using sqlplus to connect to the database instance and query v$asm_diskgroup. My ORACLE_HOME points to the home of my database instance. When I connect without specifying a "@CONNECTION" (e.g using: sqlplus user/name), then the view v$asm_diskgroup returns no rows. When I connect specifying a @TNSNAME (e.g: sqlplus user/name@TNSNAME ), then the view v$asm_diskgroup returns data correctly. Also, when I connect using sql developer, from another machine, the v$asm_diskgroup returns the rows. Why are no v$asm_diskgroup rows returned when I use sqlplus without @CONNECTION, that is, the default logon?