Android - AutoCompleteTextView not showing after setText is called

Yes you are right there is a bug in AutocompleteTextview to show default suggestion using setText(""); method.

But you can achieve this by adding some more lines of code as below.

autoText.postDelayed(new Runnable() {
            @Override
            public void run() {
                autoText.showDropDown();
            }
        },500);
        autoText.setText("chi");
        autoText.setSelection(autoText.getText().length());

It is due to filtering, No Need to any extra code for manage it, I found it in very easy and working way.

Google Dev. Reference link

autoText.setText("Default Value here",false)
autoText.setSelection(autoText.text.count()) // kotlin

as per documentation second parameter you can pass for filtering.

boolean: If false, no filtering will be performed as a result of this call.