Platform, device version and operating system:
Xbox one, but probably all platforms played with a controller.
Screenshot or image:
Link to video below.
What you were expecting to happen, and what actually happened:
After the last delve was introduced, players can now create Stone Blocks. It so happens that you can now also get locked out of your game with no way to freely move around or regain control of your pointer unless you select a troop that happens to be full mana and cast it, otherwise retreat is the only option.
How often does this happen? When did it begin happening?
Since stone blocks are a thing.
Steps to make it happen again
Position yourself on any gem of any color.
See it shaking.
Then cast a spell that creates a stone block.
Apply RNG: have the gem color you chose convert into a stone block.
Done. You can now officially not move.
Sorry for the messy link