Bug - quest recruits do not suffice

[Puzzletrainthema]

All 6 panels are green but the quest does not finish
have reloaded page
logged out and restarted
restarted laptop
restarted router
I am using buffs to achieve target
I built a new building and it completed - coincidence ??????

[topgearfan]

yes it happens when you use buffs to achieve target. start/stop a building also works