ComboBox loses the user input when losing focus (Vaadin 8)

I am trying to create a text field with auto suggestion and for that I want to use the combobox functionalty. The user should be able to either select a value or type something else.
It almost works.
When the value is typed, the user can press Enter or Tab key and then the combobox correctly fires the newItemHandler. However, if the user simply clicks somewhere else with the mouse without first pressing Enter or Tab, then the combo box clears the typed text and the user input is lost.
I can add a BlurListener to catch the moment when the focus is lost, but it is of no use for my case, because I cannot find a method that would give me the text that the user has typed into the combobox. Combobox.getValue() returns null.
I think that If there was a method that could give me the typed text, that would solve my problem.
Here is the example code:

VerticalLayout layout = new VerticalLayout();
List<String> items = new ArrayList<>();

ComboBox<String> comboBox = new ComboBox<>();

comboBox.setNewItemHandler(new ComboBox.NewItemHandler() {
  @Override public void accept(String s) {

// A dummy button. Clicking on it moves the focus and the combo forgets the input.
Button button = new Button("Click me to lose your input");
layout.addComponents(comboBox, button);

This is Vaadin 8. I tried the same thing in Vaadin 7 and it worked well. I also found this old discussion which seems to suggest that losing the user input is not a desired behaviour and is already fixed:

So may be this is an issue that has resurfaced?

I guess this was
(fixed in 8.1.0.rc2).

I have the same problem with Vaadin 8.11.0 (iPad OS 13.6).
A simple Text-Combobox with a new item handler and a button. If i typed in a new text in the combo and press the button the Combobox.getValue method returns NULL.

The same test on Chrome works for me.