I believe this is a bug as I've followed all the guides. I have a comboboxfield that is populated via remote store. If I select a valid value from the picker then click on the trigger/dropdown again it makes a call out to the server, shows the picker for a split second then disapppears and wipes out the combobox input control. I do want it to do an allQuery which it appears to do and it is returning the expected data just not displaying the picker. Here is a fiddler example:

https://fiddle.sencha.com/#view/editor&fiddle/33fq