I am using pc version , I had the same bug where it shows 'build mine ' even though I started building it but after ending the turn it again asks to build mine ,I have spent 5× resources , Don't worry it will show like that , after 8 turns it will be built , ignore it's stupid status , don't spend extra resources like me .
Although the real bug is it doesn't shows that it is being building , instead shows 'build mine' still the building will be completed exactly 8 turns.