Autocomplete doesn't work for commands with numbers of parameters

Hi!

When I run iex, type is_ and press Tab I see the following output:

is_atom/1         is_binary/1       is_bitstring/1    is_boolean/1      
is_float/1        is_function/1     is_function/2     is_integer/1      
is_list/1         is_map/1          is_nil/1          is_number/1       
is_pid/1          is_port/1         is_reference/1    is_tuple/1

However, If I do the same in IElixir, I don't see a list of functions for completion. However it works for when there is only one choice to complete, for example typing is_bool and pressing Tab completes it to is_boolean correctly.