Combobox remote filtering closes picker and clears value

Question

I am trying to get a combobox in the Ext JS 7.X modern toolkit to do remote filtering. I expect the picker with a limited number of matching records to stay open while the user can continue typing to specifically find the record the user is looking for. I can not get this to work correctly, it seems to behave inconsistently.

Here is what is actually happening:

1. The user clicks the combobox and starts typing
2. The combobox fires a http-request passing the currently typed string as param and opens the picker (masked, loading animation)
3. Sometimes (randomly?) the typed value stays in the combobox, sometimes it gets cleared
4. Most times (randomly?) the picker showing a set of matching records will collapse/close as soon as the store updates the records using the new data from backend

I tried to create a minimal fiddle using records from "0" to "999" (1000 records can be searched/filtered): https://fiddle.sencha.com/#view/editor&fiddle/3p7t

I came across a similar problem asked here but the solution is targeting the classic toolkit and from looking into the modern toolkit source, I wasn't able to identify the same piece of code to override.

I am looking for directions on how I can get the combobox to work the way I need it to. Maybe I have just set some options that are not meant to be used together but so far I had no luck finding a solution. I hope someone can help.