I have checked your statement and it is correct. My observation:
The autocomplete works for the key events in Pega ,for mouse click it will just focus so if you are trying to paste the word using keyboard i.e CTRL+V , the keyup event will trigger and it will give you results but if you are using the paste using mouse then it will not populate the results.
First i clicked outside the autocomplete in order to remove the focus then pressed on it and Paste the text using CTRL+V, no suggestion shown. then immediately selected all the text and reused CTRL+V it worked.