Schema mane automatically appended to call from functions/procedures

	I have a few functions in my database that calls other functions under the same schema, For example  MYFUNCTION under MYSCHEMA schema includes a call to MYSCHEMA.MYFUNCTION2().   The functions have been working correctly until recently. Now these functions return an invalid stage and it seems like the compiler is appending the schema name by default. The error message is object  MYAPEXSCHEMA.MYAPEXSCHEMA is invalid.   If I change the call  in MYFUNCTION() from MYSCHEMA.MYFUNCTION2() to MYFUNCTION2() the function MYFUNCTION() will compile and run without issues   Does anyone know what is causing this behaviour? Thanks