Most visible when using Cryostasis on en enemy with several stacks of Chilled, for that long freeze duration, but may also work with crawler poison stun or flashbang incapacitation. Doesn't seem to work on any 1-turn stun, or Electrokinetic Imprint/EMP stun.
Combat ends, and the countdown timer begins for starting combat manually. Usually, the stun/stasis will wear off and then when the enemy gets free, combat will force start again, with new initiative rolls. This can be a hassle, since most likely if you're dragging out a stun it's so that you can regen psi, get out of a trap/DoT, or let an item/skill cooldown period expire. Sucks to have an enemy crack out of stun, roll a 15 on initiative, and throw two crits in your face when all you needed was one...more...turn (and would have gotten that turn under control if the combat didn't auto-end and forbid you from restarting it)
Concerned this may also be a problem with Stasis in the new psi school.