Starting a couple of days ago I have been losing a lot of stamina after missions.

For example, this morning I woke up to a full bar (6 and did a single 12 stamina dragons road mission and suddenly had 26 left. 68 - 12 != 26.

The exact same thing happened yesterday morning.

Last night I had 8 stamina after finishing a mission, then I switched screens from main menu to missions and suddenly had 4.

This has happened a number of other times where suddenly my stamina bar is literally 50% what it was before.