If a mission fails unexpectedly, please try restarting Standland app.
(If you closed the mission and return to Mission List, we are sorry but you cannot recover the progress of the previous mission.)
Standland reads data from Apple's Health app, but it seems that accessing the Health data was not successful at that time. Standland will try to read it again by restarting the app.
Also, restarting your iPhone might be helpful for stabilizing the Health app.
We are looking into this issue. Thank you for your patience.