Square boundary has vanished on HotOSM

Hi I choose or I am allocated a square to map on HotOSM but then no red boundary appears within which to map. I assume I have caused this to happen by mistake. Can anyone please let me know how to re-instate boundary to my square?

Hi, If you don’t get an answer here the Hot Tasking Manager site offers this advice :- "For help with mapping or mapping related questions, please email: mapper-support@hotosm.org "