The likeness of finding out more from the video would probably be useful! Regularly this issue does occur even from my end as well. It seems to only happen as I have been completing multiple challenges and only then would it arise from my end.
If you find the video; I'll double back but usually these are really just whether the server is at a stalemate with you or if you have a fresh connection on log in.
Suggestions: Try doing a fresh log into the game very close to the challenge you are trying for and maybe that might be able to solve it. Don't quote me though lol. Glhf