I did this too, once. I was gutted. I took the mission again and found it remembered where I'd got to. I don't know if this happens with all missions (mine was the Nature Under Threat mission from the Sage in Zora).
---
It's bad luck to be superstitious . . .Palta e decata, nan nec ilne matala.
When one goes on a journey it is not the scenery that changes, but the traveller