Open the weborder sample, Tags Form view.

Go to 2nd form (Inventory) .

Click the prompt button, we can see the initial options
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we have options starting with "a", "b", "c", "d" and so on.

Close the prompt by clicking on it, but do not select any item. the form is empty.
Now type "a". The options for a appears ok.

Do not select any, but hit ESC, then BACKSPACE, to clear the form again.

Now, type "a", or "b", or "c" or any other letter that should bring a match.. Nothing happens. The prompt list is not shown.

Actually, it blinks pretty fast, so I guess it's showing but closing out very fast.

The issue is NOT observed in the 3rd form (Static source) .
Tested in Edge, Chrome, and FF