I've been encountering this lately and couldn't find it reported in a search. It's not confined to particular planet types or situations; it's just a UI thing. The Eco Bars disappear as the UI zooms out and enters 'Annihilate Mode' after you select 'Annihilate' on your KEW in the Planet dropdown. My current workaround is to go into Game Settings after this happens and click 'Save and Close' - that brings the top UI back.
It got brought up in http://pa.lennardf1989.com/Tracker/...3&project=1&order=history&sort=desc&pagenum=2 The comments there mention another temporary workaround: hitting F5.
