tripod mode drifts

Sometimes when I fly and want to switch over to tripod it is right there alongside the other modes for me to choose from. But other times, like today, I can the Mavic in the air and went to the flight modes section and tripod mode wasn't available to select. Why is that? Please help!

I have experienced this 2x times now using tripod mode. First time I was flying in the snow with obstacle avoidance system on. Mavic would have a hard time staying in a straight line when moving forward and it would go slightly up and down on altitude randomly (minor variance) Second time was...