In the report we have mainly two tabs, one is "Allocated Space Usage by Database" and the other one is "Outstanding Tablespace Full Alerts by Database". The databases listed in the Outstanding Tablespace Full Alerts by Database where not displaying in the Allocated Space Usage by Database. this is the main issue i am facing
We had the same problem in 12c EM. This had to something with "tablespace allocation metric". This metric was disabled for some databases. This could be your case in 11g also. This metalink note might worth seeing .
Oracle Database Tablespace Monthly Space Usage shows no data (Doc ID 1536654.1)