What about Non-Public Synonyms in a different schema, but with which you have rights?
For our example, we have a table FACT_CLAIM, originally in DW.FACT_CLAIM, but now we have a synonym in it's place which points to another schema (DWLOAD1.FACT_CLAIM)
When I type 'DW.FACT_' I don't see either of the FACT tables that have synonyms for that schema.
But if I run 'Select * from DW.FACT_CLAIM', of course I can use/see the table.