I run the following code which works for ALL CUSIPS except those that begin with a letter
response = symbol_conversion.Definition(
    symbols=["G1151C101", "G5494J103", "56585A102", "22822V101"],
    from_symbol_type=symbol_conversion.SymbolTypes.CUSIP,
    to_symbol_types=[
        symbol_conversion.SymbolTypes.RIC,
    ],
).get_data()
response.data.df
any ideas?
thanks 
Jeff